FamPlex

Identifier Description In Out Syn. Xref
5_hydroxytryptamine_receptors_G_protein_coupled 5 1 0 1
5_hydroxytryptamine_receptors_ionotropic A subclass of serotonin receptors that form cation channels and mediate signal transduction by depolarizing the cell membrane. The cation channels are formed from 5 receptor subunits. When stimulated the receptors allow the selective passage of SODIUM; POTASSIUM; and CALCIUM. 5 2 0 2
9_1_1 3 0 4 1
A4GALT_family 2 1 0 0
ABL_family Retrovirus-associated DNA sequences (abl) originally isolated from the Abelson murine leukemia virus (Ab-MuLV). The proto-oncogene abl (c-abl) codes for a protein that is a member of the tyrosine kinase family. The human c-abl gene is located at 9q34.1 on the long arm of chromosome 9. It is activated by translocation to bcr on chromosome 22 in chronic myelogenous leukemia. 2 0 2 4
ACAD A flavoprotein oxidoreductase that has specificity for medium-chain fatty acids. It forms a complex with ELECTRON TRANSFERRING FLAVOPROTEINS and conveys reducing equivalents to UBIQUINONE. 11 0 3 4
ACC A carboxylating enzyme that catalyzes the conversion of ATP, acetyl-CoA, and HCO3- to ADP, orthophosphate, and malonyl-CoA. It is a biotinyl-protein that also catalyzes transcarboxylation. The plant enzyme also carboxylates propanoyl-CoA and butanoyl-CoA (From Enzyme Nomenclature, 1992) EC 6.4.1.2. 2 0 5 5
Acetyl_CoA_synthetase An enzyme that catalyzes the formation of CoA derivatives from ATP, acetate, and CoA to form AMP, pyrophosphate, and acetyl CoA. It acts also on propionates and acrylates. EC 6.2.1.1. 2 0 7 2
ACOX An enzyme that catalyzes the first and rate-determining steps of peroxisomal beta-oxidation of fatty acids. It acts on COENZYME A derivatives of fatty acids with chain lengths from 8 to 18, using FLAVIN-ADENINE DINUCLEOTIDE as a cofactor. 4 0 2 4
ACSL 5 1 2 1
Actin Filamentous proteins that are the main constituent of the thin filaments of muscle fibers. The filaments (known also as filamentous or F-actin) can be dissociated into their globular subunits; each subunit is composed of a single polypeptide 375 amino acids long. This is known as globular or G-actin. In conjunction with MYOSINS, actin is responsible for the contraction and relaxation of muscle. 2 0 2 8
Actin_related_proteins 20 0 5 1
Activin Activins are produced in the pituitary, gonads, and other tissues. By acting locally, they stimulate pituitary FSH secretion and have diverse effects on cell differentiation and embryonic development. Activins are glycoproteins that are hetero- or homodimers of INHIBIN-BETA SUBUNITS. 3 0 4 6
Activin_A 1 1 5 4
Activin_AB 2 1 1 4
Activin_B 1 1 1 2
ACTN A protein factor that regulates the length of R-actin. It is chemically similar, but immunochemically distinguishable from actin. 4 0 1 3
ADA 8 1 0 1
Adaptor_protein A class of proteins involved in the transport of molecules via TRANSPORT VESICLES. They perform functions such as binding to the cell membrane, capturing cargo molecules and promoting the assembly of CLATHRIN. The majority of adaptor proteins exist as multi-subunit complexes, however monomeric varieties have also been found. 5 0 1 2
Adaptor_protein_I A clathrin adaptor protein complex primarily involved in clathrin-related transport at the TRANS-GOLGI NETWORK. 7 1 0 3
Adaptor_protein_II An adaptor protein complex primarily involved in the formation of clathrin-related endocytotic vesicles (ENDOSOMES) at the CELL MEMBRANE. 4 1 9 5
Adaptor_protein_III An adaptor protein complex found primarily on perinuclear compartments. 4 1 3 4
Adaptor_protein_IV An adaptor protein complex involved in transport of molecules between the TRANS-GOLGI NETWORK and the endosomal-lysosomal system. 4 1 0 2
Adaptor_protein_V 4 1 0 1
ADCY Enzymes of the lyase class that catalyze the formation of CYCLIC AMP and pyrophosphate from ATP. 10 0 2 5
Adenosine_deaminase_family 7 0 1 1
ADH A zinc-containing enzyme which oxidizes primary and secondary alcohols or hemiacetals in the presence of NAD. In alcoholic fermentation, it catalyzes the final step of reducing an aldehyde to an alcohol in the presence of NADH and hydrogen. 8 0 1 5
ADORA 4 1 0 0
ADRA Cell-surface proteins that bind epinephrine and/or norepinephrine with high affinity and trigger intracellular changes. The two major classes of adrenergic receptors, alpha and beta, were originally discriminated based on their cellular actions but now are distinguished by their relative affinity for characteristic synthetic ligands. Adrenergic receptors may also be classified according to the subtypes of G-proteins with which they bind; this scheme does not respect the alpha-beta distinction. 6 0 9 4
ADRA2 3 0 9 4
ADRB One of two major pharmacologically defined classes of adrenergic receptors. The beta adrenergic receptors play an important role in regulating CARDIAC MUSCLE contraction, SMOOTH MUSCLE relaxation, and GLYCOGENOLYSIS. 3 0 8 5
ADRBK G-protein-coupled receptor kinases that mediate agonist-dependent PHOSPHORYLATION and desensitization of BETA-ADRENERGIC RECEPTORS. 2 1 5 3
AGTR An angiotensin receptor subtype that is expressed at high levels in fetal tissues. Many effects of the angiotensin type 2 receptor such as VASODILATION and sodium loss are the opposite of that of the ANGIOTENSIN TYPE 1 RECEPTOR. 2 0 5 2
AKT Protein-serine-threonine kinases that contain PLECKSTRIN HOMOLOGY DOMAINS and are activated by PHOSPHORYLATION in response to GROWTH FACTORS or INSULIN. They play a major role in cell metabolism, growth, and survival as a core component of SIGNAL TRANSDUCTION. Three isoforms have been described in mammalian cells. 3 0 6 14
ALDH An enzyme that oxidizes an aldehyde in the presence of NAD+ and water to an acid and NADH. This enzyme was formerly classified as EC 1.1.1.70. 10 0 4 4
ALDO An enzyme of the lyase class that catalyzes the cleavage of fructose 1,6-biphosphate to form dihydroxyacetone phosphate and glyceraldehyde 3-phosphate. The enzyme also acts on (3S,4R)-ketose 1-phosphates. The yeast and bacterial enzymes are zinc proteins. (Enzyme Nomenclature, 1992) E.C. 4.1.2.13. 3 0 2 6
ALG10 2 1 5 0
ALG13_family 2 1 0 0
ALG1_family 10 1 0 0
ALG3_family 9 1 0 0
ALG6_family 2 1 8 1
AMPK Intracellular signaling protein kinases that play a signaling role in the regulation of cellular energy metabolism. Their activity largely depends upon the concentration of cellular AMP which is increased under conditions of low energy or metabolic stress. AMP-activated protein kinases modify enzymes involved in LIPID METABOLISM, which in turn provide substrates needed to convert AMP into ATP. 15 0 2 11
AMPK_A1B1G1 3 1 8 0
AMPK_A1B1G2 3 1 8 0
AMPK_A1B1G3 3 1 8 0
AMPK_A1B2G1 3 1 8 0
AMPK_A1B2G2 3 1 8 0
AMPK_A1B2G3 3 1 5 0
AMPK_A2B1G1 3 1 8 0
AMPK_A2B1G2 3 1 5 0
AMPK_A2B1G3 3 1 5 0
AMPK_A2B2G1 3 1 8 0
AMPK_A2B2G2 3 1 8 4
AMPK_A2B2G3 3 1 8 0
AMPK_alpha 2 1 3 7
AMPK_beta 2 1 1 5
AMPK_gamma 3 1 1 4
Annexin_II_heterotetramer 2 0 4 2
ANO A family of transmembrane proteins that function primarily as calcium-activated chloride channels. Structurally, they form a homodimer where each subunit consists of eight transmembrane helices with the N and C terminals exposed to the cytosol. The regions between helices 5 and 7 may be important for ion pore formation and calcium ion binding. 10 1 0 2
AP1 A multiprotein complex composed of the products of c-jun and c-fos proto-oncogenes. These proteins must dimerize in order to bind to the AP-1 recognition site, also known as the TPA-responsive element (TRE). AP-1 controls both basal and inducible transcription of several genes. 2 0 2 3
AP2A A family of large adaptin protein subunits of approximately 100 kDa in size. They have been primarily found as components of ADAPTOR PROTEIN COMPLEX 2. 2 1 0 2
APC_C An E3 ubiquitin ligase primarily involved in regulation of the metaphase-to-anaphase transition during MITOSIS through ubiquitination of specific CELL CYCLE PROTEINS. Enzyme activity is tightly regulated through subunits and cofactors, which modulate activation, inhibition, and substrate specificity. The anaphase-promoting complex, or APC-C, is also involved in tissue differentiation in the PLACENTA, CRYSTALLINE LENS, and SKELETAL MUSCLE, and in regulation of postmitotic NEURONAL PLASTICITY and excitability. 14 0 1 5
APOA Structural proteins of the alpha-lipoproteins (HIGH DENSITY LIPOPROTEINS), including APOLIPOPROTEIN A-I and APOLIPOPROTEIN A-II. They can modulate the activity of LECITHIN CHOLESTEROL ACYLTRANSFERASE. These apolipoproteins are low in atherosclerotic patients. They are either absent or present in extremely low plasma concentration in TANGIER DISEASE. 4 1 6 3
Apolipoprotein Protein components on the surface of LIPOPROTEINS. They form a layer surrounding the hydrophobic lipid core. There are several classes of apolipoproteins with each playing a different role in lipid transport and LIPID METABOLISM. These proteins are synthesized mainly in the LIVER and the INTESTINES. 2 0 3 4
AQP A class of porins that allow the passage of WATER and other small molecules across CELL MEMBRANES. 14 1 0 2
ARF_GTPase_family MONOMERIC GTP-BINDING PROTEINS that were initially recognized as allosteric activators of the MONO(ADP-RIBOSE) TRANSFERASE of the CHOLERA TOXIN catalytic subunit. They are involved in vesicle trafficking and activation of PHOSPHOLIPASE D. This enzyme was formerly listed as EC 3.6.1.47 31 0 1 1
Arp2_3_protein A complex of seven proteins including ARP2 PROTEIN and ARP3 PROTEIN that plays an essential role in maintenance and assembly of the CYTOSKELETON. Arp2-3 complex binds WASP PROTEIN and existing ACTIN FILAMENTS, and it nucleates the formation of new branch point filaments. 7 0 1 2
ARRB Non-visual system arrestins that negatively regulate G-PROTEIN-COUPLED RECEPTORS (GPCRs) and may also function independently of GPCR signaling. They bind and recruit many different signaling factors, including MITOGEN-ACTIVATED PROTEIN KINASES; SRC-FAMILY-KINASES; and FILAMIN to GPCRs and may recognize different phosphorylation states of the receptors to determine the specificity of the cellular response to signaling. 2 0 2 3
ASIC A family of proton-gated sodium channels that are primarily expressed in neuronal tissue. They are AMILORIDE-sensitive and are implicated in the signaling of a variety of neurological stimuli, most notably that of pain in response to acidic conditions. 5 2 0 2
ATG4 4 0 2 1
ATP1A 4 1 7 1
ATP1B 4 1 3 1
ATP5G 3 1 1 3
ATP_synthase Multisubunit enzyme complexes that synthesize ADENOSINE TRIPHOSPHATE from energy sources such as ions traveling through channels. 18 0 1 3
Augmin 8 0 3 4
AXIN A scaffolding protein that is a critical component of the axin signaling complex which binds to ADENOMATOUS POLYPOSIS COLI PROTEIN; GLYCOGEN SYNTHASE KINASE 3; and CASEIN KINASE I. 2 0 2 8
Axonemal_dynein Dyneins that are responsible for ciliary and flagellar beating. 2 1 1 2
Axonemal_dynein_IDA 17 1 0 1
Axonemal_dynein_ODA 14 1 1 1
B3GAT 3 1 5 0
BCKDC 4 0 6 4
BDKR Cell surface receptors that bind BRADYKININ and related KININS with high affinity and trigger intracellular changes which influence the behavior of cells. The identified receptor types (B-1 and B-2, or BK-1 and BK-2) recognize endogenous KALLIDIN; t-kinins; and certain bradykinin fragments as well as bradykinin itself. 2 0 2 3
BEST A protein family characterized by a highly conserved N-terminus and four to six transmembrane helices; they function as bicarbonate permeable, calcium-activated chloride channels. Bestrophin-1 (BEST-1) and bestrophin-2 are highly expressed in human RETINAL PIGMENT EPITHELIUM cells and mutations in the BEST-1 gene are associated with VITELLIFORM MACULAR DYSTROPHY, TYPE 2. 4 1 0 2
Beta_3_4_GTF 37 1 8 0
Beta_HEX 2 1 2 0
BIRC A conserved class of proteins that control APOPTOSIS in both VERTEBRATES and INVERTEBRATES. IAP proteins interact with and inhibit CASPASES, and they function as ANTI-APOPTOTIC PROTEINS. The protein class is defined by an approximately 80-amino acid motif called the baculoviral inhibitor of apoptosis repeat; some members have ubiquitin-protein ligase activity. 8 0 1 3
BLVR 2 0 1 1
BMP Bone-growth regulatory factors that are members of the transforming growth factor-beta superfamily of proteins. They are synthesized as large precursor molecules which are cleaved by proteolytic enzymes. The active form can consist of a dimer of two identical proteins or a heterodimer of two related bone morphogenetic proteins. 17 0 1 4
BMP_receptor A family of CELL SURFACE RECEPTORS that bind BONE MORPHOGENETIC PROTEINS. They are PROTEIN-SERINE-THREONINE KINASES that mediate SIGNAL TRANSDUCTION PATHWAYS through SMAD PROTEINS. 2 0 0 2
BMP_receptor_type_I A subtype of bone morphogenetic protein receptors with high affinity for BONE MORPHOGENETIC PROTEINS. They can interact with and undergo PHOSPHORYLATION by BONE MORPHOGENETIC PROTEIN RECEPTORS, TYPE II. They signal primarily through RECEPTOR-REGULATED SMAD PROTEINS. 3 1 7 3
BMP_receptor_type_II A subtype of bone morphogenetic protein receptors with low affinity for BONE MORPHOGENETIC PROTEINS. They are constitutively active PROTEIN-SERINE-THREONINE KINASES that can interact with and phosphorylate TYPE I BONE MORPHOGENETIC PROTEIN RECEPTORS. 3 1 6 4
BRCA 2 0 1 0
BRISC_complex 4 1 6 2
C1 The first complement component to act in the activation of CLASSICAL COMPLEMENT PATHWAY. It is a calcium-dependent trimolecular complex made up of three subcomponents: COMPLEMENT C1Q; COMPLEMENT C1R; and COMPLEMENT C1S at 1:2:2 ratios. When the intact C1 binds to at least two antibodies (involving C1q), C1r and C1s are sequentially activated, leading to subsequent steps in the cascade of COMPLEMENT ACTIVATION. 5 0 3 5
C1q A subcomponent of complement C1, composed of six copies of three polypeptide chains (A, B, and C), each encoded by a separate gene (C1QA; C1QB; C1QC). This complex is arranged in nine subunits (six disulfide-linked dimers of A and B, and three disulfide-linked homodimers of C). C1q has binding sites for antibodies (the heavy chain of IMMUNOGLOBULIN G or IMMUNOGLOBULIN M). The interaction of C1q and immunoglobulin activates the two proenzymes COMPLEMENT C1R and COMPLEMENT C1S, thus initiating the cascade of COMPLEMENT ACTIVATION via the CLASSICAL COMPLEMENT PATHWAY. 2 0 1 2
CACN Voltage-dependent calcium channels ( VDCC ) are a group of voltage-gated ion channels found in the membrane of excitable cells ( e.g., muscle, glial cells, neurons, etc.) with a permeability to the calcium ion Ca 2+. These channels are slightly permeable to sodium ions, so they are also called Ca 2+ -Na + channels, but their permeability to calcium is about 1000-fold greater than to sodium under normal physiological conditions. At physiologic or resting membrane potential, VDCCs are normally closed. They are activated ( i.e., opened) at depolarized membrane potentials and this is the source of the 'voltage-dependent' epithet. The concentration of calcium (Ca 2+ ions) is normally several thousand times higher outside of the cell than inside. Activation of particular VDCCs allows Ca 2+ to rush into the cell, which, depending on the cell type, results in activation of calcium-sensitive potassium channels, muscular contraction, excitation of neurons, up-regulation of gene expression, or release of hormones or neurotransmitters. Excessive activation of VDCCs is a major component of excitotoxicity, as severely elevated levels of intracellular calcium activates enzymes which, at high enough levels, can degrade essential cellular structures. 4 2 0 1
CACNA1 Voltage-dependent calcium channels ( VDCCs ) are a group of voltage-gated ion channels found in the membrane of excitable cells ( e.g., muscle, glial cells, neurons, etc.) with a permeability to the calcium ion Ca 2+. These channels are slightly permeable to sodium ions, so they are also called Ca 2+ -Na + channels, but their permeability to calcium is about 1000-fold greater than to sodium under normal physiological conditions. At physiologic or resting membrane potential, VDCCs are normally closed. They are activated ( i.e., opened) at depolarized membrane potentials and this is the source of the 'voltage-dependent' epithet. The concentration of calcium (Ca 2+ ions) is normally several thousand times higher outside of the cell than inside. Activation of particular VDCCs allows Ca 2+ to rush into the cell, which, depending on the cell type, results in activation of calcium-sensitive potassium channels, muscular contraction, excitation of neurons, up-regulation of gene expression, or release of hormones or neurotransmitters. VDCCs have been immunolocalized in the zona glomerulosa of normal and hyperplastic human adrenal, as well as in aldosterone -producing adenomas (APA), and in the latter T-type VDCCs correlated with plasma aldosterone levels of patients. Excessive activation of VDCCs is a major component of excitotoxicity, as severely elevated levels of intracellular calcium activates enzymes which, at high enough levels, can degrade essential cellular structures. 10 1 0 1
CACNA2D Voltage-dependent calcium channels ( VDCCs ) are a group of voltage-gated ion channels found in the membrane of excitable cells ( e.g., muscle, glial cells, neurons, etc.) with a permeability to the calcium ion Ca 2+. These channels are slightly permeable to sodium ions, so they are also called Ca 2+ -Na + channels, but their permeability to calcium is about 1000-fold greater than to sodium under normal physiological conditions. At physiologic or resting membrane potential, VDCCs are normally closed. They are activated ( i.e., opened) at depolarized membrane potentials and this is the source of the 'voltage-dependent' epithet. The concentration of calcium (Ca 2+ ions) is normally several thousand times higher outside of the cell than inside. Activation of particular VDCCs allows Ca 2+ to rush into the cell, which, depending on the cell type, results in activation of calcium-sensitive potassium channels, muscular contraction, excitation of neurons, up-regulation of gene expression, or release of hormones or neurotransmitters. VDCCs have been immunolocalized in the zona glomerulosa of normal and hyperplastic human adrenal, as well as in aldosterone -producing adenomas (APA), and in the latter T-type VDCCs correlated with plasma aldosterone levels of patients. Excessive activation of VDCCs is a major component of excitotoxicity, as severely elevated levels of intracellular calcium activates enzymes which, at high enough levels, can degrade essential cellular structures. 4 1 0 1
CACNB Voltage-gated calcium channels (VGCCs), also known as voltage-dependent calcium channels (VDCCs), are a group of voltage-gated ion channels found in the membrane of excitable cells (e.g., muscle, glial cells, neurons, etc.) with a permeability to the calcium ion Ca2+. These channels are slightly permeable to sodium ions, so they are also called Ca2+-Na+ channels, but their permeability to calcium is about 1000-fold greater than to sodium under normal physiological conditions. At physiologic or resting membrane potential, VGCCs are normally closed. They are activated (i.e., opened) at depolarized membrane potentials and this is the source of the 'voltage-gated' epithet. The concentration of calcium (Ca2+ ions) is normally several thousand times higher outside the cell than inside. Activation of particular VGCCs allows a Ca2+ influx into the cell, which, depending on the cell type, results in activation of calcium-sensitive potassium channels, muscular contraction, excitation of neurons, up-regulation of gene expression, or release of hormones or neurotransmitters. VGCCs have been immunolocalized in the zona glomerulosa of normal and hyperplastic human adrenal, as well as in aldosterone-producing adenomas (APA), and in the latter T-type VGCCs correlated with plasma aldosterone levels of patients. Excessive activation of VGCCs is a major component of excitotoxicity, as severely elevated levels of intracellular calcium activates enzymes which, at high enough levels, can degrade essential cellular structures. 4 1 0 1
CACNG Voltage-dependent calcium channels ( VDCCs ) are a group of voltage-gated ion channels found in the membrane of excitable cells ( e.g., muscle, glial cells, neurons, etc.) with a permeability to the calcium ion Ca 2+. These channels are slightly permeable to sodium ions, so they are also called Ca 2+ -Na + channels, but their permeability to calcium is about 1000-fold greater than to sodium under normal physiological conditions. At physiologic or resting membrane potential, VDCCs are normally closed. They are activated ( i.e., opened) at depolarized membrane potentials and this is the source of the 'voltage-dependent' epithet. The concentration of calcium (Ca 2+ ions) is normally several thousand times higher outside of the cell than inside. Activation of particular VDCCs allows Ca 2+ to rush into the cell, which, depending on the cell type, results in activation of calcium-sensitive potassium channels, muscular contraction, excitation of neurons, up-regulation of gene expression, or release of hormones or neurotransmitters. VDCCs have been immunolocalized in the zona glomerulosa of normal and hyperplastic human adrenal, as well as in aldosterone -producing adenomas (APA), and in the latter T-type VDCCs correlated with plasma aldosterone levels of patients. Excessive activation of VDCCs is a major component of excitotoxicity, as severely elevated levels of intracellular calcium activates enzymes which, at high enough levels, can degrade essential cellular structures. 8 1 0 1
Cadherin Calcium-dependent cell adhesion proteins. They are important in the formation of ADHERENS JUNCTIONS between cells. Cadherins are classified by their distinct immunological and tissue specificities, either by letters (E- for epithelial, N- for neural, and P- for placental cadherins) or by numbers (cadherin-12 or N-cadherin 2 for brain-cadherin). Cadherins promote cell adhesion via a homophilic mechanism as in the construction of tissues and of the whole animal body. 21 0 1 6
Calcium_channels Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue. 5 1 4 2
Calcium_sensing_receptors A class of G-protein-coupled receptors that react to varying extracellular CALCIUM levels. Calcium-sensing receptors in the PARATHYROID GLANDS play an important role in the maintenance of calcium HOMEOSTASIS by regulating the release of PARATHYROID HORMONE. They differ from INTRACELLULAR CALCIUM-SENSING PROTEINS which sense intracellular calcium levels. 2 1 0 2
CALM A heat-stable, low-molecular-weight activator protein found mainly in the brain and heart. The binding of calcium ions to this protein allows this protein to bind to cyclic nucleotide phosphodiesterases and to adenyl cyclase with subsequent activation. Thereby this protein modulates cyclic AMP and cyclic GMP levels. 3 0 3 6
CAMK A CALMODULIN-dependent enzyme that catalyzes the phosphorylation of proteins. This enzyme is also sometimes dependent on CALCIUM. A wide range of proteins can act as acceptor, including VIMENTIN; SYNAPSINS; GLYCOGEN SYNTHASE; MYOSIN LIGHT CHAINS; and the MICROTUBULE-ASSOCIATED PROTEINS. (From Enzyme Nomenclature, 1992, p277) 5 0 3 4
CAMK2_complex A multifunctional calcium-calmodulin-dependent protein kinase subtype that occurs as an oligomeric protein comprised of twelve subunits. It differs from other enzyme subtypes in that it lacks a phosphorylatable activation domain that can respond to CALCIUM-CALMODULIN-DEPENDENT PROTEIN KINASE KINASE. 4 0 15 8
CAMK2_family 4 1 0 6
CAP Adenylate cyclase associated (CAP) N terminal 2 0 2 2
CAPN Cysteine proteinase found in many tissues. Hydrolyzes a variety of endogenous proteins including NEUROPEPTIDES; CYTOSKELETAL PROTEINS; proteins from SMOOTH MUSCLE; CARDIAC MUSCLE; liver; platelets; and erythrocytes. Two subclasses having high and low calcium sensitivity are known. Removes Z-discs and M-lines from myofibrils. Activates phosphorylase kinase and cyclic nucleotide-independent protein kinase. This enzyme was formerly listed as EC 3.4.22.4. 14 0 1 7
Carboxylesterase Carboxylesterase is a serine-dependent esterase with wide substrate specificity. The enzyme is involved in the detoxification of XENOBIOTICS and the activation of ester and of amide PRODRUGS. 5 0 2 4
Caspase A family of intracellular CYSTEINE ENDOPEPTIDASES that play a role in regulating INFLAMMATION and APOPTOSIS. They specifically cleave peptides at a CYSTEINE amino acid that follows an ASPARTIC ACID residue. Caspases are activated by proteolytic cleavage of a precursor form to yield large and small subunits that form the enzyme. Since the cleavage site within precursors matches the specificity of caspases, sequential activation of precursors by activated caspases can occur. 11 0 2 7
Caspase_3_7 2 1 1 1
Cathepsin A group of lysosomal proteinases or endopeptidases found in aqueous extracts of a variety of animal tissues. They function optimally within an acidic pH range. The cathepsins occur as a variety of enzyme subtypes including SERINE PROTEASES; ASPARTIC PROTEINASES; and CYSTEINE PROTEASES. 15 0 2 2
Cation_channels 3 0 4 0
CATSPER The cation channels of sperm also known as Catsper channels or CatSper, are ion channels that are related to the two-pore channels and distantly related to TRP channels. The four members of this family form voltage-gated Ca 2+ channels that seem to be specific to sperm. As sperm encounter the more alkaline environment of the female reproductive tract, CatSper channels become activated by the altered ion concentration. These channels are required for proper fertilization. The study of these channels has been slow because they do not traffic to the cell membrane in many heterologous systems. 7 2 0 1
CAV Caveolin 3 0 2 6
CBF3 SKP1 (together with SKP2) was identified as an essential component of the cyclin A-CDK2 S phase kinase complex 1 0 3 4
CCL Group of chemokines with adjacent cysteines that are chemoattractants for lymphocytes, monocytes, eosinophils, basophils but not neutrophils. 42 0 0 1
CCT_complex A group II chaperonin found in eukaryotic CYTOSOL. It is comprised of eight subunits with each subunit encoded by a separate gene. This chaperonin is named after one of its subunits which is a T-COMPLEX REGION-encoded polypeptide. 9 0 7 7
CD16 2 0 1 2
CD3 Complex of at least five membrane-bound polypeptides in mature T-lymphocytes that are non-covalently associated with one another and with the T-cell receptor (RECEPTORS, ANTIGEN, T-CELL). The CD3 complex includes the gamma, delta, epsilon, zeta, and eta chains (subunits). When antigen binds to the T-cell receptor, the CD3 complex transduces the activating signals to the cytoplasm of the T-cell. The CD3 gamma and delta chains (subunits) are separate from and not related to the gamma/delta chains of the T-cell receptor (RECEPTORS, ANTIGEN, T-CELL, GAMMA-DELTA). 4 0 1 4
CD32 3 0 1 2
CD64 2 0 1 4
CD8 Differentiation antigens found on thymocytes and on cytotoxic and suppressor T-lymphocytes. T8 antigens are members of the immunoglobulin supergene family and are associative recognition elements in MHC (Major Histocompatibility Complex) Class I-restricted interactions. 2 0 1 3
CDC25 A subclass of dual specificity phosphatases that play a role in the progression of the CELL CYCLE. They dephosphorylate and activate CYCLIN-DEPENDENT KINASES. 3 0 4 6
CDK Protein kinases that control cell cycle progression in all eukaryotes and require physical association with CYCLINS to achieve full enzymatic activity. Cyclin-dependent kinases are regulated by phosphorylation and dephosphorylation events. 25 0 4 4
CDK1_2 2 1 3 0
CDK_activating_kinase_complex 3 0 1 1
CDKN A group of cell cycle proteins that negatively regulate the activity of CYCLIN/CYCLIN-DEPENDENT KINASE complexes. They inhibit CELL CYCLE progression and help control CELL PROLIFERATION following GENOTOXIC STRESS as well as during CELL DIFFERENTIATION. 3 0 5 3
CDKN1 3 1 2 4
CDKN2 4 1 1 0
CEBP A class of proteins that were originally identified by their ability to bind the DNA sequence CCAAT. The typical CCAAT-enhancer binding protein forms dimers and consists of an activation domain, a DNA-binding basic region, and a leucine-rich dimerization domain (LEUCINE ZIPPERS). CCAAT-BINDING FACTOR is structurally distinct type of CCAAT-enhancer binding protein consisting of a trimer of three different subunits. 5 0 2 3
CHEK 2 0 2 1
Chemokine Class of pro-inflammatory cytokines that have the ability to attract and activate leukocytes. They can be divided into at least three structural branches: C; (CHEMOKINES, C); CC; (CHEMOKINES, CC); and CXC; (CHEMOKINES, CXC); according to variations in a shared cysteine motif. 2 0 2 3
Chemokine_receptor Cell surface glycoproteins that bind to chemokines and thus mediate the migration of pro-inflammatory molecules. The receptors are members of the seven-transmembrane G protein-coupled receptor family. Like the CHEMOKINES themselves, the receptors can be divided into at least three structural branches: CR, CCR, and CXCR, according to variations in a shared cysteine motif. 22 0 1 2
CHK An enzyme that is active in the first step of choline phosphoglyceride (lecithin) biosynthesis by catalyzing the phosphorylation of choline to phosphorylcholine in the presence of ATP. Ethanolamine and its methyl and ethyl derivatives can also act as acceptors. EC 2.7.1.32. 2 0 3 1
Chloride_calcium_activated_channels 2 1 0 1
Chloride_channels Cell membrane glycoproteins that form channels to selectively pass chloride ions. Nonselective blockers include FENAMATES; ETHACRYNIC ACID; and TAMOXIFEN. 5 0 0 2
Cholinesterase 2 0 2 6
CHRM One of the two major classes of cholinergic receptors. Muscarinic receptors were originally defined by their preference for MUSCARINE over NICOTINE. There are several subtypes (usually M1, M2, M3....) that are characterized by their cellular actions, pharmacology, and molecular biology. 5 0 1 3
CHRN One of the two major classes of cholinergic receptors. Nicotinic receptors were originally distinguished by their preference for NICOTINE over MUSCARINE. They are generally divided into muscle-type and neuronal-type (previously ganglionic) based on pharmacology, and subunit composition of the receptors. 16 1 3 4
CK2 A ubiquitous casein kinase that is comprised of two distinct catalytic subunits and dimeric regulatory subunit. Casein kinase II has been shown to phosphorylate a large number of substrates, many of which are proteins involved in the regulation of gene expression. 3 1 4 7
Clathrin The main structural coat protein of COATED VESICLES which play a key role in the intracellular transport between membranous organelles. Each molecule of clathrin consists of three light chains (CLATHRIN LIGHT CHAINS) and three heavy chains (CLATHRIN HEAVY CHAINS) that form a structure called a triskelion. Clathrin also interacts with cytoskeletal proteins. 3 0 2 6
CLCN 10 1 0 1
CLEC A C-type lectin (CLEC) is a type of carbohydrate-binding protein domain known as a lectin. The C-type designation is from their requirement for calcium for binding. Proteins that contain C-type lectin domains have a diverse range of functions including cell-cell adhesion, immune response to pathogens and apoptosis. 84 0 0 1
CLIC 6 1 0 1
CLK CLK family members have shown to interact with, and phosphorylate, serine / arginine -rich (SR) proteins of the spliceosomal complex, which is a part of the regulatory mechanism that enables the SR proteins to control RNA splicing. 4 0 0 2
CNG A subgroup of cyclic nucleotide-regulated ION CHANNELS within the superfamily of pore-loop cation channels. They are expressed in OLFACTORY NERVE cilia and in PHOTORECEPTOR CELLS and some PLANTS. 10 1 0 2
CNKSR 2 0 2 1
Cofilin A family of low MOLECULAR WEIGHT actin-binding proteins found throughout eukaryotes. They remodel the actin CYTOSKELETON by severing ACTIN FILAMENTS and increasing the rate of monomer dissociation. 3 0 1 2
Cohesin Cohesin domain 2 0 2 6
COL1 The most common form of fibrillar collagen. It is a major constituent of bone (BONE AND BONES) and SKIN and consists of a heterotrimer of two alpha1(I) and one alpha2(I) chains. 2 0 3 17
COL4 A non-fibrillar collagen found in the structure of BASEMENT MEMBRANE. Collagen type IV molecules assemble to form a sheet-like network which is involved in maintaining the structural integrity of basement membranes. The predominant form of the protein is comprised of two alpha1(IV) subunits and one alpha2(IV) subunit, however, at least six different alpha subunits can be incorporated into the heterotrimer. 6 0 5 6
COL5 A fibrillar collagen found widely distributed as a minor component in tissues that contain COLLAGEN TYPE I and COLLAGEN TYPE III. It is a heterotrimeric molecule composed of alpha1(V), alpha2(V) and alpha3(V) subunits. Several forms of collagen type V exist depending upon the composition of the subunits that form the trimer. 3 0 3 5
COLGALT 2 1 5 0
COX A multisubunit enzyme complex containing CYTOCHROME A GROUP; CYTOCHROME A3; two copper atoms; and 13 different protein subunits. It is the terminal oxidase complex of the RESPIRATORY CHAIN and collects electrons that are transferred from the reduced CYTOCHROME C GROUP and donates them to molecular OXYGEN, which is then reduced to water. The redox reaction is simultaneously coupled to the transport of PROTONS across the inner mitochondrial membrane. 13 0 2 7
COX4 Cytochrome c oxidase subunit IV 2 1 1 4
COX6A Cytochrome c oxidase subunit VIa 2 1 3 4
COX6B Cytochrome oxidase c subunit VIb 2 1 1 2
COX7A Cytochrome c oxidase subunit VII 2 1 2 2
COX7B Cytochrome C oxidase chain VIIB 2 1 1 4
COX8 Cytochrome oxidase c subunit VIII 2 1 2 3
Creatine_kinase A transferase that catalyzes formation of PHOSPHOCREATINE from ATP + CREATINE. The reaction stores ATP energy as phosphocreatine. Three cytoplasmic ISOENZYMES have been identified in human tissues: the MM type from SKELETAL MUSCLE, the MB type from myocardial tissue and the BB type from nervous tissue as well as a mitochondrial isoenzyme. Macro-creatine kinase refers to creatine kinase complexed with other serum proteins. 6 0 1 1
CREB A protein that has been shown to function as a calcium-regulated transcription factor as well as a substrate for depolarization-activated CALCIUM-CALMODULIN-DEPENDENT PROTEIN KINASES. This protein functions to integrate both calcium and cAMP signals. 10 0 2 4
CRISP Crisp 3 0 4 4
CRSP 7 0 4 3
CRTC 3 0 1 0
CSNK A group of protein-serine-threonine kinases that was originally identified as being responsible for the PHOSPHORYLATION of CASEINS. They are ubiquitous enzymes that have a preference for acidic proteins. Casein kinases play a role in SIGNAL TRANSDUCTION by phosphorylating a variety of regulatory cytoplasmic and regulatory nuclear proteins. 2 0 1 1
CSNK1 A casein kinase that was originally described as a monomeric enzyme with a molecular weight of 30-40 kDa. Several ISOENZYMES of casein kinase I have been found which are encoded by separate genes. Many of the casein kinase I isoenzymes have been shown to play distinctive roles in intracellular SIGNAL TRANSDUCTION. 7 1 9 4
CSNK2 2 0 1 5
CTNNA A catenin that binds F-ACTIN and links the CYTOSKELETON with BETA CATENIN and GAMMA CATENIN. 3 0 7 2
CUL A family of structurally related proteins that were originally discovered for their role in cell-cycle regulation in CAENORHABDITIS ELEGANS. They play important roles in regulation of the CELL CYCLE and as components of UBIQUITIN-PROTEIN LIGASES. 7 0 3 6
CXCL_ELR_negative 7 1 4 1
CXCL_ELR_positive 7 1 3 1
Cyclin A large family of regulatory proteins that function as accessory subunits to a variety of CYCLIN-DEPENDENT KINASES. They generally function as ENZYME ACTIVATORS that drive the CELL CYCLE through transitions between phases. A subset of cyclins may also function as transcriptional regulators. 21 0 4 4
Cyclin_A A cyclin subtype that has specificity for CDC2 PROTEIN KINASE and CYCLIN-DEPENDENT KINASE 2. It plays a role in progression of the CELL CYCLE through G1/S and G2/M phase transitions. 2 1 3 7
Cyclin_B 3 1 1 0
Cyclin_D A cyclin subtype that is specific for CYCLIN-DEPENDENT KINASE 4 and CYCLIN-DEPENDENT KINASE 6. Unlike most cyclins, cyclin D expression is not cyclical, but rather it is expressed in response to proliferative signals. Cyclin D may therefore play a role in cellular responses to mitogenic signals. 3 1 2 8
Cyclin_E A 50-kDa protein that complexes with CYCLIN-DEPENDENT KINASE 2 in the late G1 phase of the cell cycle. 2 1 1 9
Cyclin_G 2 1 1 0
Cyclophilin A family of peptidyl-prolyl cis-trans isomerases that bind to CYCLOSPORINS and regulate the IMMUNE SYSTEM. EC 5.2.1.- 17 0 2 3
CYP A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism. 19 0 26 2
CYP1 A cytochrome P450 enzyme family whose members function primarily in the metabolism of XENOBIOTICS, including drugs and POLYCYCLIC AROMATIC HYDROCARBONS. 3 1 3 2
CYP11 A cytochrome P450 enzyme family whose members localize to the INNER MITOCHONDRIAL MEMBRANE where they function in the biosynthesis of STEROIDS. 3 1 0 2
CYP2 A cytochrome P450 enzyme family that includes members which function in the metabolism of STEROIDS; COUMARINS; and NICOTINE. 17 1 1 2
CYP26 A cytochrome P450 enzyme family whose members function in the metabolism of RETINOIC ACID. It includes RETINOIC ACID 4-HYDROXYLASE. 3 1 1 2
CYP27 A cytochrome P450 enzyme family whose members function in VITAMIN D metabolism and the biosynthesis of BILE ACIDS. 3 1 0 2
CYP3 A cytochrome P450 enzyme family that includes members with critical functions in the metabolism of drugs and SEX HORMONES. 4 1 4 2
CYP4 A cytochrome P450 enzyme family that includes members which function in the metabolism of FATTY ACIDS, especially ARACHIDONIC ACIDS and their derivatives. 12 1 1 2
CYP7 A cytochrome P450 enzyme family whose members function as steroid 7-alpha hydroxylases. 2 1 0 2
CYP8 A cytochrome P450 enzyme family whose members include prostacyclin synthase and STEROID 12-ALPHA-HYDROXYLASE, which function in the biosynthesis of BILE ACIDS. 2 1 0 2
CYP_epoxygenases 15 1 2 0
Cytoplasmic_dynein Dyneins that are responsible for intracellular transport, MITOSIS, cell polarization, and movement within the cell. 2 1 3 4
DAPK A family of calcium/calmodulin-dependent PROETIN-SERINE-THREONINE KINASES. They are ubiquitously expressed in adult and embryonic mammalian tissues, and their functions are tightly related to the early stages of eukaryotic programmed cell death. 5 0 2 2
DDR Receptor tyrosine kinases that bind COLLAGENS. They are characterized by the presence of extracellular DISCOIDIN DOMAINS that activate SIGNAL TRANSDUCTION PATHWAYS in response to collagen binding. They may also be cleaved by MATRIX METALLOPROTEINASES to mediate cell interactions with the EXTRACELLULAR MATRIX. 2 0 3 4
Death_receptor A family of cell surface receptors that signal via a conserved domain that extends into the cell CYTOPLASM. The conserved domain is referred to as a DEATH DOMAIN due to the fact that many of these receptors are involved in APOPTOSIS signaling pathways. Several DEATH DOMAIN RECEPTOR SIGNALING ADAPTOR PROTEINS can bind to the death domains of the activated receptors and through a complex series of interactions activate apoptotic mediators such as CASPASES. 7 0 2 2
Deoxyribonucleoside_kinases 3 0 0 2
DESI 2 1 8 1
Desmoglein A group of desmosomal cadherins with cytoplasmic tails that resemble those of classical CADHERINS. 4 0 2 6
Desumoylase 3 0 0 1
Deubiquitinase 10 0 31 3
DGC 12 0 5 3
DGK An enzyme of the transferase class that uses ATP to catalyze the phosphorylation of diacylglycerol to a phosphatidate. EC 2.7.1.107. 10 0 5 5
DNA_polymerase_alpha 4 0 10 1
DNA_polymerase_delta A DNA-dependent DNA polymerase characterized in E. coli and other lower organisms but may be present in higher organisms. Use also for a more complex form of DNA polymerase III designated as DNA polymerase III* or pol III* which is 15 times more active biologically than DNA polymerase I in the synthesis of DNA. This polymerase has both 3'-5' and 5'-3' exonuclease activities, is inhibited by sulfhydryl reagents, and has the same template-primer dependence as pol II. EC 2.7.7.7. 4 0 6 5
DNM A family of high molecular weight GTP phosphohydrolases that play a direct role in vesicle transport. They associate with microtubule bundles (MICROTUBULES) and are believed to produce mechanical force via a process linked to GTP hydrolysis. This enzyme was formerly listed as EC 3.6.1.50. 3 0 2 6
DNMT 4 1 0 1
DRD Cell-surface proteins that bind dopamine with high affinity and trigger intracellular changes influencing the behavior of cells. 5 0 2 5
DUSP A sub-class of protein tyrosine phosphatases that contain an additional phosphatase activity which cleaves phosphate ester bonds on SERINE or THREONINE residues that are located on the same protein. 6 0 1 1
DVL A family of proteins that are key components of the WNT SIGNALING PATHWAY, where they function downstream of FRIZZLED RECEPTORS. They contain an N-terminal dishevelled-AXIN PROTEIN (DIX) domain, which mediates oligomerization; a central PDZ DOMAIN which binds to the frizzled receptor; and a C-terminal DEP domain which facilitates binding to the CELL MEMBRANE. Dishevelled proteins have important functions in CELL DIFFERENTIATION and establishing CELL POLARITY. 3 0 2 12
DYNC1 Cytoplasmic dynein-1 is a major microtubule-based motor critical for cell division. Dynein is essential for the formation and positioning of the mitotic spindle as well as the transport of various cargos in the cell. 11 1 0 1
DYNC2 The motor protein that powers the movement of the particles from the tip of the flagellum to the base (retrograde IFT) is called cytoplasmic dynein 1b in Chlamydomonas and cytoplasmic dynein 2 in vertebrates. 11 1 0 1
Dynein A family of multisubunit cytoskeletal motor proteins that use the energy of ATP hydrolysis, generated by a ring of AAA ATPASES in the dynein heavy chain, to power a variety of cellular functions. Dyneins fall into two major classes based upon structural and functional criteria. 2 0 11 2
DYRK 5 0 1 1
E2F A family of basic helix-loop-helix transcription factors that control expression of a variety of GENES involved in CELL CYCLE regulation. E2F transcription factors typically form heterodimeric complexes with TRANSCRIPTION FACTOR DP1 or transcription factor DP2, and they have N-terminal DNA binding and dimerization domains. E2F transcription factors can act as mediators of transcriptional repression or transcriptional activation. 8 0 1 5
E3_Ub_ligase A diverse class of enzymes that interact with UBIQUITIN-CONJUGATING ENZYMES and ubiquitination-specific protein substrates. Each member of this enzyme group has its own distinct specificity for a substrate and ubiquitin-conjugating enzyme. Ubiquitin-protein ligases exist as both monomeric proteins multiprotein complexes. 0 0 2 3
EDN 21-Amino-acid peptides produced by vascular endothelial cells and functioning as potent vasoconstrictors. The endothelin family consists of three members, ENDOTHELIN-1; ENDOTHELIN-2; and ENDOTHELIN-3. All three peptides contain 21 amino acids, but vary in amino acid composition. The three peptides produce vasoconstrictor and pressor responses in various parts of the body. However, the quantitative profiles of the pharmacological activities are considerably different among the three isopeptides. 3 1 2 9
EDNR Cell surface proteins that bind ENDOTHELINS with high affinity and trigger intracellular changes which influence the behavior of cells. 2 0 4 1
EEF 3 0 1 0
EEF1 2 1 0 0
EEF1A 2 1 0 0
EEF1B 3 1 0 0
EFN Signaling proteins that are ligands for the EPH FAMILY RECEPTORS. They are membrane-bound proteins that are attached to the CELL MEMBRANE either through a GLYCOINOSITOL PHOSPHOLIPID MEMBRANE ANCHOR or through a transmembrane domain. Many of the ephrins are considered important intercellular signaling molecules that control morphogenic changes during embryogenesis. 8 0 2 2
EGFR_ligand A family of proteins that are related to epidermal growth factor. They share in common a consensus sequence consisting of six spatially conserved CYSTEINE residues which form three intramolecular bonds. This consensus sequence is commonly referred to EGF motif and is considered essential for binding of the proteins to ERB RECEPTORS. 7 0 2 3
EGR A family of transcription factors that are induced by GROWTH FACTORS and contain a highly conserved DNA-binding domain composed of three ZINC FINGER MOTIFS. 4 0 2 2
EIF2B A guanine nucleotide exchange factor that acts to restore EUKARYOTIC INITIATION FACTOR-2 to its GTP bound form. 5 0 2 4
EIF4 A trimeric peptide initiation factor complex that associates with the 5' MRNA cap structure of RNA (RNA CAPS) and plays an essential role in MRNA TRANSLATION. It is composed of EUKARYOTIC INITIATION FACTOR-4A; EUKARYOTIC INITIATION FACTOR-4E; and EUKARYOTIC INITIATION FACTOR-4G. 3 0 0 1
EIF4A A component of eukaryotic initiation factor 4F that as an RNA helicase involved in unwinding the secondary structure of the 5' UNTRANSLATED REGION of MRNA. The unwinding facilitates the binding of the 40S ribosomal subunit. 3 1 2 4
EIF4E 3 1 0 0
EIF4EBP 3 0 2 3
EIF4G A component of eukaryotic initiation factor-4F that is involved in multiple protein interactions at the site of translation initiation. Thus it may serve a role in bringing together various initiation factors at the site of translation initiation. 3 1 1 3
ELA A protease of broad specificity, obtained from dried pancreas. Molecular weight is approximately 25,000. The enzyme breaks down elastin, the specific protein of elastic fibers, and digests other proteins such as fibrin, hemoglobin, and albumin. EC 3.4.21.36. 9 0 1 3
ENO A hydro-lyase that catalyzes the dehydration of 2-phosphoglycerate to form PHOSPHOENOLPYRUVATE. Several different isoforms of this enzyme exist, each with its own tissue specificity. 4 0 1 6
Eotaxin 3 0 2 0
EPHA 9 1 0 0
EPHB 5 1 1 0
Ephrin_receptor A large family of receptor protein-tyrosine kinases that are structurally-related. The name of this family of proteins derives from original protein Eph (now called the EPHA1 RECEPTOR), which was named after the cell line it was first discovered in: Erythropoietin-Producing human Hepatocellular carcinoma cell line. Members of this family have been implicated in regulation of cell-cell interactions involved in nervous system patterning and development. 2 0 3 8
EPN 4 0 2 3
ERBB A family of structurally-related cell-surface receptors that signal through an intrinsic PROTEIN-TYROSINE KINASE. The receptors are activated upon binding of specific ligands which include EPIDERMAL GROWTH FACTORS, and NEUREGULINS. 4 0 2 5
ERK A mitogen-activated protein kinase subfamily that is widely expressed and plays a role in regulation of MEIOSIS; MITOSIS; and post mitotic functions in differentiated cells. The extracellular signal regulated MAP kinases are regulated by a broad variety of CELL SURFACE RECEPTORS and can be activated by certain CARCINOGENS. 2 1 22 18
ERM 3 0 4 0
ESR Cytoplasmic proteins that bind estrogens and migrate to the nucleus where they regulate DNA transcription. Evaluation of the state of estrogen receptors in breast cancer patients has become clinically important. 2 0 2 2
ETC_complex_I A flavoprotein and iron sulfur-containing oxidoreductase complex that catalyzes the conversion of UBIQUINONE to ubiquinol. In MITOCHONDRIA the complex also couples its reaction to the transport of PROTONS across the internal mitochondrial membrane. The NADH DEHYDROGENASE component of the complex can be isolated and is listed as EC 1.6.99.3. 2 0 0 6
ETC_complex_I_core 14 1 0 1
ETC_complex_II A flavoprotein oxidase complex that contains iron-sulfur centers. It catalyzes the oxidation of SUCCINATE to fumarate and couples the reaction to the reduction of UBIQUINONE to ubiquinol. 4 0 3 9
ETC_complex_III A multisubunit enzyme complex that contains CYTOCHROME B GROUP; CYTOCHROME C1; and iron-sulfur centers. It catalyzes the oxidation of ubiquinol to UBIQUINONE, and transfers the electrons to CYTOCHROME C. In MITOCHONDRIA the redox reaction is coupled to the transport of PROTONS across the inner mitochondrial membrane. 10 0 2 7
ETC_complex_I_supernumerary 30 1 0 1
ETC_complex_V Proton-translocating ATPases responsible for ADENOSINE TRIPHOSPHATE synthesis in the MITOCHONDRIA. They derive energy from the respiratory chain-driven reactions that develop high concentrations of protons within the intermembranous space of the mitochondria. 0 0 0 4
ETNK 2 0 0 1
ETS A family of transcription factors that share a unique DNA-binding domain. The name derives from viral oncogene-derived protein oncogene protein v-ets of the AVIAN ERYTHROBLASTOSIS VIRUS. 2 0 1 7
EXOC 8 0 3 3
EXT 5 1 3 0
FABP 16 0 1 1
F_actin 6 1 2 2
FANC A diverse group of proteins whose genetic MUTATIONS have been associated with the chromosomal instability syndrome FANCONI ANEMIA. Many of these proteins play important roles in protecting CELLS against OXIDATIVE STRESS. 20 0 2 1
FERMT The [fermitin or] kindlin family of proteins each contain a bipartite FERM domain comprising four subdomains F0, F1, F2, and F3 that show homology with the FERM head (H) domain of the cytoskeletal Talin protein. Kindlins have been linked to Kindler syndrome, leukocyte adhesion deficiency, cancer and other acquired human diseases. They are essential in the organisation of focal adhesions that mediate cell-extracellular matrix junctions and are involved in other cellular compartments that control cell-cell contacts and nucleus functioning. Therefore they are responsible for cell to cell crosstalk via cell-cell contacts and integrin mediated cell adhesion through focal adhesion proteins and as specialised adhesion structures of hematopoietic cells they are also present in podosome's F actin surrounding ring structure. 3 0 8 2
FGF A family of small polypeptide growth factors that share several common features including a strong affinity for HEPARIN, and a central barrel-shaped core region of 140 amino acids that is highly homologous between family members. Although originally studied as proteins that stimulate the growth of fibroblasts this distinction is no longer a requirement for membership in the fibroblast growth factor family. 22 0 1 6
FGFR Specific molecular sites or structures on cell membranes that react with FIBROBLAST GROWTH FACTORS (both the basic and acidic forms), their analogs, or their antagonists to elicit or to inhibit the specific response of the cell to these factors. These receptors frequently possess tyrosine kinase activity. 5 0 1 6
Fibrin A protein derived from FIBRINOGEN in the presence of THROMBIN, which forms part of the blood clot. 3 0 1 2
Fibrinogen Plasma glycoprotein clotted by thrombin, composed of a dimer of three non-identical pairs of polypeptide chains (alpha, beta, gamma) held together by disulfide bonds. Fibrinogen clotting is a sol-gel change involving complex molecular arrangements: whereas fibrinogen is cleaved by thrombin to form polypeptides A and B, the proteolytic action of other enzymes yields different fibrinogen degradation products. 3 0 1 11
FLOT Flotillin 2 0 1 7
FLRT 3 0 3 2
FNR An integrin found in FIBROBLASTS; PLATELETS; MONOCYTES, and LYMPHOCYTES. Integrin alpha5beta1 is the classical receptor for FIBRONECTIN, but it also functions as a receptor for LAMININ and several other EXTRACELLULAR MATRIX PROTEINS. 2 1 5 2
FNT An enzyme that catalyzes the synthesis of geranylgeranyl diphosphate from trans, trans-farnesyl diphosphate and isopentenyl diphosphate. 2 0 3 3
FOS_family 4 1 2 1
FOX A subclass of winged helix DNA-binding proteins that share homology with their founding member fork head protein, Drosophila. 19 0 0 1
FOXA 3 1 4 0
FOXB 2 1 2 0
FOXC 2 1 2 0
FOXD 5 1 4 0
FOXD4L 5 1 1 0
FOXE 2 1 1 0
FOXF 2 1 7 0
FOXI 3 1 1 0
FOXJ 3 1 1 0
FOXK 2 1 6 0
FOXL 2 1 2 0
FOXN 4 1 1 0
FOXO 4 1 2 4
FOXP 4 1 6 0
FOXR 2 1 2 0
FPR A family of G-protein-coupled receptors that was originally identified by its ability to bind N-formyl peptides such as N-FORMYLMETHIONINE LEUCYL-PHENYLALANINE. Since N-formyl peptides are found in MITOCHONDRIA and BACTERIA, this class of receptors is believed to play a role in mediating cellular responses to cellular damage and bacterial invasion. However, non-formylated peptide ligands have also been found for this receptor class. 3 0 0 2
FSH A major gonadotropin secreted by the human adenohypophysis (PITUITARY GLAND, ANTERIOR). Follicle-stimulating hormone stimulates GAMETOGENESIS and the supporting cells such as the ovarian GRANULOSA CELLS, the testicular SERTOLI CELLS, and the LEYDIG CELLS. FSH consists of two noncovalently linked subunits, alpha and beta. The alpha subunit is common in the three human pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity. 2 0 2 4
FUT Enzymes catalyzing the transfer of fucose from a nucleoside diphosphate fucose to an acceptor molecule which is frequently another carbohydrate, a glycoprotein, or a glycolipid molecule. Elevated activity of some fucosyltransferases in human serum may serve as an indicator of malignancy. The class includes EC 2.4.1.65; EC 2.4.1.68; EC 2.4.1.69; EC 2.4.1.89. 13 1 5 1
FZD A family of seven-pass transmembrane cell-surface proteins that combines with LOW DENSITY LIPROTEIN RECEPTOR-RELATED PROTEIN-5 or LOW DENSITY LIPROTEIN RECEPTOR-RELATED PROTEIN-5 to form receptors for WNT PROTEINS. Frizzled receptors often couple with HETEROTRIMERIC G PROTEINS and regulate the WNT SIGNALING PATHWAY. 10 0 2 7
G_12 1 1 4 4
G_12_alpha A ubiquitously expressed family of heterotrimeric GTP-binding protein alpha subunits that signal through interactions with a variety of second messengers as GTPASE-ACTIVATING PROTEINS; GUANINE NUCLEOTIDE EXCHANGE FACTORS; and HEAT SHOCK PROTEINS. The G12-G13 part of the name is also spelled G12/G13. 2 2 5 5
GABBR A subset of GABA RECEPTORS that signal through their interaction with HETEROTRIMERIC G-PROTEINS. 2 1 0 2
GABR Cell-surface proteins that bind GAMMA-AMINOBUTYRIC ACID with high affinity and trigger changes that influence the behavior of cells. GABA-A receptors control chloride channels formed by the receptor complex itself. They are blocked by bicuculline and usually have modulatory sites sensitive to benzodiazepines and barbiturates. GABA-B receptors act through G-proteins on several effector systems, are insensitive to bicuculline, and have a high affinity for L-baclofen. 19 1 5 4
G_actin 6 1 2 0
GAD A pyridoxal-phosphate protein that catalyzes the alpha-decarboxylation of L-glutamic acid to form gamma-aminobutyric acid and carbon dioxide. The enzyme is found in bacteria and in invertebrate and vertebrate nervous systems. It is the rate-limiting enzyme in determining GAMMA-AMINOBUTYRIC ACID levels in normal nervous tissues. The brain enzyme also acts on L-cysteate, L-cysteine sulfinate, and L-aspartate. EC 4.1.1.15. 2 0 2 1
GALNT 20 1 1 0
G_alpha The GTPase-containing subunits of heterotrimeric GTP-binding proteins. When dissociated from the heterotrimeric complex these subunits interact with a variety of second messenger systems. Hydrolysis of GTP by the inherent GTPase activity of the subunit causes it to revert to its inactive (heterotrimeric) form. The GTP-Binding protein alpha subunits are grouped into families according to the type of action they have on second messenger systems. 4 0 6 2
Gamma_secretase 3 0 3 4
GAP Proteins that activate the GTPase of specific GTP-BINDING PROTEINS. 0 0 4 3
GARP 4 0 0 0
GAS6_receptor 3 0 1 1
GATA A family of transcription factors that contain two ZINC FINGER MOTIFS and bind to the DNA sequence (A/T)GATA(A/G). 6 0 2 5
G_beta Heterotrimeric GTP-binding protein subunits that tightly associate with GTP-BINDING PROTEIN GAMMA SUBUNITS. A dimer of beta and gamma subunits is formed when the GTP-BINDING PROTEIN ALPHA SUBUNIT dissociates from the GTP-binding protein heterotrimeric complex. The beta-gamma dimer can play an important role in signal transduction by interacting with a variety of second messengers. 5 0 6 9
GCNT 7 1 6 0
GEF 0 0 2 2
G_gamma Heterotrimeric GTP-binding protein subunits that tightly associate with GTP-BINDING PROTEIN BETA SUBUNITS. A dimer of beta and gamma subunits is formed when the GTP-BINDING PROTEIN ALPHA SUBUNIT dissociates from the GTP-binding protein heterotrimeric complex. The beta-gamma dimer can play an important role in signal transduction by interacting with a variety of second messengers. 12 0 4 7
G_i 1 1 2 6
G_i_alpha A family of heterotrimeric GTP-binding protein alpha subunits that were originally identified by their ability to inhibit ADENYLYL CYCLASES. Members of this family can couple to beta and gamma G-protein subunits that activate POTASSIUM CHANNELS. The Gi-Go part of the name is also spelled Gi/Go. 8 2 10 7
GJ A group of homologous proteins which form the intermembrane channels of GAP JUNCTIONS. The connexins are the products of an identified gene family which has both highly conserved and highly divergent regions. The variety contributes to the wide range of functional properties of gap junctions. 21 0 4 2
GLRA_GLRB Cell surface receptors that bind GLYCINE with high affinity and trigger intracellular changes which influence the behavior of cells. Glycine receptors in the CENTRAL NERVOUS SYSTEM have an intrinsic chloride channel and are usually inhibitory. 5 1 0 2
Glycosyltransferase Enzymes that catalyze the transfer of glycosyl groups to an acceptor. Most often another carbohydrate molecule acts as an acceptor, but inorganic phosphate can also act as an acceptor, such as in the case of PHOSPHORYLASES. Some of the enzymes in this group also catalyze hydrolysis, which can be regarded as transfer of a glycosyl group from the donor to water. Subclasses include the HEXOSYLTRANSFERASES; PENTOSYLTRANSFERASES; SIALYLTRANSFERASES; and those transferring other glycosyl groups. EC 2.4. 25 0 0 1
GNRH A decapeptide that stimulates the synthesis and secretion of both pituitary gonadotropins, LUTEINIZING HORMONE and FOLLICLE STIMULATING HORMONE. GnRH is produced by neurons in the septum PREOPTIC AREA of the HYPOTHALAMUS and released into the pituitary portal blood, leading to stimulation of GONADOTROPHS in the ANTERIOR PITUITARY GLAND. 2 1 8 2
GOT Enzymes of the transferase class that catalyze the conversion of L-aspartate and 2-ketoglutarate to oxaloacetate and L-glutamate. EC 2.6.1.1. 2 0 4 1
GPCR The largest family of cell surface receptors involved in SIGNAL TRANSDUCTION. They share a common structure and signal through HETEROTRIMERIC G-PROTEINS. 1 0 2 6
GPCR_C The class C G-protein-coupled receptors (IPR000337) are a class of G-protein coupled receptors that include the metabotropic glutamate receptors (IPR000162) and several additional receptors. Family C GPCRs have a large extracellular N-terminus which binds the orthosteric (endogenous) ligand. The shape of this domain is often likened to a clam. Several allosteric ligands to these receptors have been identified and these bind within the seven transmembrane region. 4 1 1 1
GPCR_C_orphans This set contains class C 'orphan' G protein coupled receptors where the endogenous ligand(s) is not known. 7 1 0 1
GPIb_IX_V Platelet membrane glycoprotein complex essential for normal platelet adhesion and clot formation at sites of vascular injury. It is composed of three polypeptides, GPIb alpha, GPIb beta, and GPIX. Glycoprotein Ib functions as a receptor for von Willebrand factor and for thrombin. Congenital deficiency of the GPIb-IX complex results in Bernard-Soulier syndrome. The platelet glycoprotein GPV associates with GPIb-IX and is also absent in Bernard-Soulier syndrome. 4 0 6 5
GPIT 5 0 4 2
G_protein Regulatory proteins that act as molecular switches. They control a wide range of biological processes including: receptor signaling, intracellular signal transduction pathways, and protein synthesis. Their activity is regulated by factors that control their ability to bind to and hydrolyze GTP to GDP. EC 3.6.1.-. 4 0 2 2
GPX An enzyme catalyzing the oxidation of 2 moles of glutathione in the presence of hydrogen peroxide to yield oxidized glutathione and water. EC 1.11.1.9. 8 0 1 7
G_q 1 1 2 10
G_q_alpha A family of heterotrimeric GTP-binding protein alpha subunits that activate TYPE C PHOSPHOLIPASES dependent signaling pathways. The Gq-G11 part of the name is also spelled Gq/G11. 4 2 10 10
GRI A class of ligand-gated ion channel receptors that have specificity for GLUTAMATE. They are distinct from METABOTROPIC GLUTAMATE RECEPTORS which act through a G-protein-coupled mechanism. 4 1 0 2
GRIA A class of ionotropic glutamate receptors characterized by their affinity for the agonist AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid). 4 1 6 8
GRID 2 1 0 1
GRIN A class of ionotropic glutamate receptors characterized by affinity for N-methyl-D-aspartate. NMDA receptors have an allosteric binding site for glycine which must be occupied for the channel to open efficiently and a site within the channel itself to which magnesium ions bind in a voltage-dependent manner. The positive voltage dependence of channel conductance and the high permeability of the conducting channel to calcium ions (as well as to monovalent cations) are important in excitotoxicity and neuronal plasticity. 7 1 4 3
GRK A family of serine-threonine kinases that are specific for G-PROTEIN-COUPLED RECEPTORS. They are regulatory proteins that play a role in G-protein-coupled receptor densensitization. 6 0 4 5
GRM Cell surface proteins that bind glutamate and act through G-proteins to influence second messenger systems. Several types of metabotropic glutamate receptors have been cloned. They differ in pharmacology, distribution, and mechanisms of action. 8 1 4 6
G_s 1 1 5 1
G_s_alpha A family of heterotrimeric GTP-binding protein alpha subunits that activate ADENYLYL CYCLASES. 2 2 14 1
GSK3 A glycogen synthase kinase that was originally described as a key enzyme involved in glycogen metabolism. It regulates a diverse array of functions such as CELL DIVISION, microtubule function and APOPTOSIS. 2 0 2 6
GST A transferase that catalyzes the addition of aliphatic, aromatic, or heterocyclic FREE RADICALS as well as EPOXIDES and arene oxides to GLUTATHIONE. Addition takes place at the SULFUR. It also catalyzes the reduction of polyol nitrate by glutathione to polyol and nitrite. 18 0 4 4
GTF2E 2 0 4 4
GTF2F 2 0 4 5
GTF_family_2 6 1 2 0
GTF_family_29 A group of enzymes with the general formula CMP-N-acetylneuraminate:acceptor N-acetylneuraminyl transferase. They catalyze the transfer of N-acetylneuraminic acid from CMP-N-acetylneuraminic acid to an acceptor, which is usually the terminal sugar residue of an oligosaccharide, a glycoprotein, or a glycolipid. EC 2.4.99.-. 20 1 6 1
GTF_family_6 4 1 2 0
GTF_family_8 10 1 2 0
GTF_family_90 3 1 2 0
GTPase Enzymes that hydrolyze GTP to GDP. EC 3.6.1.-. 0 0 1 4
GUCY An enzyme that catalyzes the conversion of GTP to 3',5'-cyclic GMP and pyrophosphate. It also acts on ITP and dGTP. (From Enzyme Nomenclature, 1992) EC 4.6.1.2. 5 0 2 4
GUCY1A 2 1 0 0
GUCY1B 2 1 0 0
GYS An enzyme that catalyzes the transfer of D-glucose from UDPglucose into 1,4-alpha-D-glucosyl chains. EC 2.4.1.11. 2 0 1 3
hCG A gonadotropic glycoprotein hormone produced primarily by the PLACENTA. Similar to the pituitary LUTEINIZING HORMONE in structure and function, chorionic gonadotropin is involved in maintaining the CORPUS LUTEUM during pregnancy. CG consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is virtually identical to the alpha subunits of the three pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity (CHORIONIC GONADOTROPIN, BETA SUBUNIT, HUMAN). 2 0 1 3
HDAC Deacetylases that remove N-acetyl groups from amino side chains of the amino acids of HISTONES. The enzyme family can be divided into at least three structurally-defined subclasses. Class I and class II deacetylases utilize a zinc-dependent mechanism. The sirtuin histone deacetylases belong to class III and are NAD-dependent enzymes. 4 0 3 6
HDAC_I 4 1 3 2
HDAC_II 6 1 2 1
HDAC_III A subclass of histone deacetylases that are NAD-dependent. Several members of the SIRTUINS family are included in this subclass. 7 1 3 3
HDAC_IV 1 1 3 0
HDL A class of lipoproteins of small size (4-13 nm) and dense (greater than 1.063 g/ml) particles. HDL lipoproteins, synthesized in the liver without a lipid core, accumulate cholesterol esters from peripheral tissues and transport them to the liver for re-utilization or elimination from the body (the reverse cholesterol transport). Their major protein component is APOLIPOPROTEIN A-I. HDL also shuttle APOLIPOPROTEINS C and APOLIPOPROTEINS E to and from triglyceride-rich lipoproteins during their catabolism. HDL plasma level has been inversely correlated with the risk of cardiovascular diseases. 5 0 2 4
Hedgehog A family of intercellular signaling proteins that play an important role in regulating the development of many TISSUES and organs. Their name derives from the observation of a hedgehog-like appearance in DROSOPHILA embryos with genetic mutations that block their action. 3 0 5 17
Hemoglobin The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements. 10 0 2 5
HES 7 0 4 1
HEX 5 0 1 2
HIF 2 0 3 2
HIF1 A basic helix-loop-helix transcription factor that plays a role in APOPTOSIS. It is composed of two subunits: ARYL HYDROCARBON RECEPTOR NUCLEAR TRANSLOCATOR and HYPOXIA-INDUCIBLE FACTOR 1, ALPHA SUBUNIT. 2 0 1 5
HIF_alpha 3 1 4 1
HIF_beta 3 1 4 1
Histone Small chromosomal proteins (approx 12-20 kD) possessing an open, unfolded structure and attached to the DNA in cell nuclei by ionic linkages. Classification into the various types (designated histone I, histone II, etc.) is based on the relative amounts of arginine and lysine in each. 5 0 3 5
Histone_H1 10 1 1 3
Histone_H2A 19 1 3 4
Histone_H2B 19 1 2 2
Histone_H3 5 1 3 5
Histone_H4 2 1 2 5
HLA_DR A subclass of HLA-D antigens that consist of alpha and beta chains. The inheritance of HLA-DR antigens differs from that of the HLA-DQ ANTIGENS and HLA-DP ANTIGENS. 5 0 1 3
HMOX A mixed function oxidase enzyme which during hemoglobin catabolism catalyzes the degradation of heme to ferrous iron, carbon monoxide and biliverdin in the presence of molecular oxygen and reduced NADPH. The enzyme is induced by metals, particularly cobalt. 2 0 2 8
HRH Cell-surface proteins that bind histamine and trigger intracellular changes influencing the behavior of cells. Histamine receptors are widespread in the central nervous system and in peripheral tissues. Three types have been recognized and designated H1, H2, and H3. They differ in pharmacology, distribution, and mode of action. 4 0 3 2
HSP90 A class of MOLECULAR CHAPERONES whose members act in the mechanism of SIGNAL TRANSDUCTION by STEROID RECEPTORS. 3 0 2 4
HSP90A 2 1 1 4
HSP90AA 1 1 1 3
HSPA A class of MOLECULAR CHAPERONES found in both prokaryotes and in several compartments of eukaryotic cells. These proteins can interact with polypeptides during a variety of assembly processes in such a way as to prevent the formation of nonfunctional structures. 16 0 3 3
HSPB 3 0 4 1
HTR Cell-surface proteins that bind SEROTONIN and trigger intracellular changes which influence the behavior of cells. Several types of serotonin receptors have been recognized which differ in their pharmacology, molecular biology, and mode of action. 2 0 0 2
HTR1 A subclass of G-protein coupled SEROTONIN receptors that couple preferentially to GI-GO G-PROTEINS resulting in decreased intracellular CYCLIC AMP levels. 4 1 0 1
HTR2 A subclass of G-protein coupled SEROTONIN receptors that couple preferentially to the GQ-G11 G-PROTEINS resulting in increased intracellular levels of INOSITOL PHOSPHATES and free CALCIUM. 3 1 0 1
HVCN 1 1 0 1
IFITM Interferon inducible transmembrane proteins have diverse roles, including the control of cell proliferation, promotion of homotypic cell adhesion, protection against viral infection, promotion of bone matrix maturation and mineralisation, and mediating germ cell development. 5 0 3 2
IFNA One of the type I interferons produced by peripheral blood leukocytes or lymphoblastoid cells. In addition to antiviral activity, it activates NATURAL KILLER CELLS and B-LYMPHOCYTES, and down-regulates VASCULAR ENDOTHELIAL GROWTH FACTOR expression through PI-3 KINASE and MAPK KINASES signaling pathways. 13 1 5 3
IFNAR A ubiquitously expressed heterodimeric receptor that is specific for both INTERFERON-ALPHA and INTERFERON-BETA. It is composed of two subunits referred to as IFNAR1 and IFNAR2. The IFNAR2 subunit is believed to serve as the ligand-binding chain; however both chains are required for signal transduction. The interferon alpha-beta receptor signals through the action of JANUS KINASES such as the TYK2 KINASE. 2 0 4 2
IFNB One of the type I interferons produced by fibroblasts in response to stimulation by live or inactivated virus or by double-stranded RNA. It is a cytokine with antiviral, antiproliferative, and immunomodulating activity. 1 1 6 3
IGFBP A family of soluble proteins that bind insulin-like growth factors and modulate their biological actions at the cellular level. (Int J Gynaecol Obstet 1992;39(1):3-9) 7 0 4 4
IKB 0 0 2 1
IKK_complex A protein serine-threonine kinase that catalyzes the PHOSPHORYLATION of I KAPPA B PROTEINS. This enzyme also activates the transcription factor NF-KAPPA B and is composed of alpha and beta catalytic subunits, which are protein kinases and gamma, a regulatory subunit. 3 0 4 11
IKK_family A family of inhibitory proteins which bind to the REL PROTO-ONCOGENE PROTEINS and modulate their activity. In the CYTOPLASM, I-kappa B proteins bind to the transcription factor NF-KAPPA B. Cell stimulation causes its dissociation and translocation of active NF-kappa B to the nucleus. 5 0 0 4
IL1 A soluble factor produced by MONOCYTES; MACROPHAGES, and other cells which activates T-lymphocytes and potentiates their response to mitogens or antigens. Interleukin-1 is a general term refers to either of the two distinct proteins, INTERLEUKIN-1ALPHA and INTERLEUKIN-1BETA. The biological effects of IL-1 include the ability to replace macrophage requirements for T-cell activation. 2 0 2 8
IL12 A heterodimeric cytokine that plays a role in innate and adaptive immune responses. Interleukin-12 is a 70 kDa protein that is composed of covalently linked 40 kDa and 35 kDa subunits. It is produced by DENDRITIC CELLS; MACROPHAGES and a variety of other immune cells and plays a role in the stimulation of INTERFERON-GAMMA production by T-LYMPHOCYTES and NATURAL KILLER CELLS. 2 0 2 8
IL15R Cell surface receptors for INTERLEUKIN-15. They are widely-distributed heterotrimeric proteins consisting of the INTERLEUKIN-15 RECEPTOR ALPHA SUBUNIT, the INTERLEUKIN-2, 15 RECEPTOR BETA SUBUNIT, and the INTERLEUKIN RECEPTOR COMMON GAMMA-CHAIN. 3 0 2 1
IL23 A heterodimeric cytokine that plays a role in innate and adaptive immune responses. Interleukin-23 is comprised of a unique 19 kDa subunit and 40 kDa subunit that is shared with INTERLEUKIN-12. It is produced by DENDRITIC CELLS; MACROPHAGES and a variety of other immune cells 2 0 7 2
IL2R Receptors present on activated T-LYMPHOCYTES and B-LYMPHOCYTES that are specific for INTERLEUKIN-2 and play an important role in LYMPHOCYTE ACTIVATION. They are heterotrimeric proteins consisting of the INTERLEUKIN-2 RECEPTOR ALPHA SUBUNIT, the INTERLEUKIN-2 RECEPTOR BETA SUBUNIT, and the INTERLEUKIN RECEPTOR COMMON GAMMA-CHAIN. 3 0 2 1
Inhibin Glycoproteins that inhibit pituitary FOLLICLE STIMULATING HORMONE secretion. Inhibins are secreted by the Sertoli cells of the testes, the granulosa cells of the ovarian follicles, the placenta, and other tissues. Inhibins and ACTIVINS are modulators of FOLLICLE STIMULATING HORMONE secretions; both groups belong to the TGF-beta superfamily, as the TRANSFORMING GROWTH FACTOR BETA. Inhibins consist of a disulfide-linked heterodimer with a unique alpha linked to either a beta A or a beta B subunit to form inhibin A or inhibin B, respectively 2 0 2 4
Inhibin_A 2 1 3 3
Inhibin_B 2 1 3 2
INSR 3 0 3 4
Integrins A family of transmembrane glycoproteins (MEMBRANE GLYCOPROTEINS) consisting of noncovalent heterodimers. They interact with a wide variety of ligands including EXTRACELLULAR MATRIX PROTEINS; COMPLEMENT, and other cells, while their intracellular domains interact with the CYTOSKELETON. The integrins consist of at least three identified families: the cytoadhesin receptors(RECEPTORS, CYTOADHESIN), the leukocyte adhesion receptors (RECEPTORS, LEUKOCYTE ADHESION), and the VERY LATE ANTIGEN RECEPTORS. Each family contains a common beta-subunit (INTEGRIN BETA CHAINS) combined with one or more distinct alpha-subunits (INTEGRIN ALPHA CHAINS). These receptors participate in cell-matrix and cell-cell adhesion in many physiologically important processes, including embryological development; HEMOSTASIS; THROMBOSIS; WOUND HEALING; immune and nonimmune defense mechanisms; and oncogenic transformation. 8 0 3 5
Interferon Proteins secreted by vertebrate cells in response to a wide variety of inducers. They confer resistance against many different viruses, inhibit proliferation of normal and malignant cells, impede multiplication of intracellular parasites, enhance macrophage and granulocyte phagocytosis, augment natural killer cell activity, and show several other immunomodulatory functions. 4 0 2 5
Interferon_gamma_receptor 2 0 5 3
IRS A structurally-related group of signaling proteins that are phosphorylated by the INSULIN RECEPTOR PROTEIN-TYROSINE KINASE. The proteins share an N-terminal PLECKSTRIN HOMOLOGY DOMAIN, a phosphotyrosine-binding domain that interacts with the phosphorylated INSULIN RECEPTOR, and a C-terminal TYROSINE-rich domain. Upon tyrosine phosphorylation, insulin receptor substrate proteins interact with specific SH2 DOMAIN containing proteins that are involved in insulin receptor signaling. 3 0 3 6
IRX 7 0 4 1
ITGA The alpha subunits of integrin heterodimers (INTEGRINS), which mediate ligand specificity. There are approximately 18 different alpha chains, exhibiting great sequence diversity; several chains are also spliced into alternative isoforms. They possess a long extracellular portion (1200 amino acids) containing a MIDAS (metal ion-dependent adhesion site) motif, and seven 60-amino acid tandem repeats, the last 4 of which form EF HAND MOTIFS. The intracellular portion is short with the exception of INTEGRIN ALPHA4. 18 1 1 2
ITGA2B1 An integrin found on fibroblasts, platelets, endothelial and epithelial cells, and lymphocytes where it functions as a receptor for COLLAGEN and LAMININ. Although originally referred to as the collagen receptor, it is one of several receptors for collagen. Ligand binding to integrin alpha2beta1 triggers a cascade of intracellular signaling, including activation of p38 MAP kinase. 2 1 1 2
ITGA2B3 2 1 1 0
ITGB Integrin beta chains combine with integrin alpha chains to form heterodimeric cell surface receptors. Integrins have traditionally been classified into functional groups based on the identity of one of three beta chains present in the heterodimer. The beta chain is necessary and sufficient for integrin-dependent signaling. Its short cytoplasmic tail contains sequences critical for inside-out signaling. 9 1 0 2
ITPR Intracellular receptors that bind to INOSITOL 1,4,5-TRISPHOSPHATE and play an important role in its intracellular signaling. Inositol 1,4,5-trisphosphate receptors are calcium channels that release CALCIUM in response to increased levels of inositol 1,4,5-trisphosphate in the CYTOPLASM. 3 2 0 2
JAK A family of intracellular tyrosine kinases that participate in the signaling cascade of cytokines by associating with specific CYTOKINE RECEPTORS. They act upon STAT TRANSCRIPTION FACTORS in signaling pathway referred to as the JAK/STAT pathway. The name Janus kinase refers to the fact the proteins have two phosphate-transferring domains. 4 0 3 5
JAMM 12 1 19 0
JNK A subgroup of mitogen-activated protein kinases that activate TRANSCRIPTION FACTOR AP-1 via the phosphorylation of C-JUN PROTEINS. They are components of intracellular signaling pathways that regulate CELL PROLIFERATION; APOPTOSIS; and CELL DIFFERENTIATION. 3 1 8 8
JUN_family 3 1 1 3
Kainate_family A class of ionotropic glutamate receptors characterized by their affinity for KAINIC ACID. 5 1 3 2
KCN Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits. 5 1 4 2
KCNH A family of voltage-gated potassium channels that are characterized by long N-terminal and C-terminal intracellular tails. They are named from the Drosophila protein whose mutation causes abnormal leg shaking under ether anesthesia. Their activation kinetics are dependent on extracellular MAGNESIUM and PROTON concentration. 8 1 0 1
KCNJ Potassium channels where the flow of K+ ions into the cell is greater than the outward flow. 16 1 2 2
KCNK Potassium channels that contain two pores in tandem. They are responsible for baseline or leak currents and may be the most numerous of all K channels. 15 3 0 2
KCNT 2 1 0 2
Kinesin A microtubule-associated mechanical adenosine triphosphatase, that uses the energy of ATP hydrolysis to move organelles along microtubules toward the plus end of the microtubule. The protein is found in squid axoplasm, optic lobes, and in bovine brain. Bovine kinesin is a heterotetramer composed of two heavy (120 kDa) and two light (62 kDa) chains. 44 0 3 3
Kinetochore Large multiprotein complexes that bind the centromeres of the chromosomes to the microtubules of the mitotic spindle during metaphase in the cell cycle. 17 0 3 3
KLK Proteolytic enzymes from the serine endopeptidase family found in normal blood and urine. Specifically, Kallikreins are potent vasodilators and hypotensives and increase vascular permeability and affect smooth muscle. They act as infertility agents in men. Three forms are recognized, PLASMA KALLIKREIN (EC 3.4.21.34), TISSUE KALLIKREIN (EC 3.4.21.35), and PROSTATE-SPECIFIC ANTIGEN (EC 3.4.21.77). 16 0 5 4
KMT 34 1 0 1
KSR 2 0 1 1
Laminin_111 3 0 1 3
Laminin_332 3 0 6 6
LATS 2 0 2 1
LDH Alcohol oxidoreductases with substrate specificity for LACTIC ACID. 3 0 1 4
LFA_1 An integrin heterodimer widely expressed on cells of hematopoietic origin. CD11A ANTIGEN comprises the alpha chain and the CD18 antigen (CD18 ANTIGENS) the beta chain. Lymphocyte function-associated antigen-1 is a major receptor of T-CELLS; B-CELLS; and GRANULOCYTES. It mediates the leukocyte adhesion reactions underlying cytolytic conjugate formation, helper T-cell interactions, and antibody-dependent killing by NATURAL KILLER CELLS and granulocytes. Intracellular adhesion molecule-1 has been defined as a ligand for lymphocyte function-associated antigen-1. 2 1 1 2
LH A major gonadotropin secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Luteinizing hormone regulates steroid production by the interstitial cells of the TESTIS and the OVARY. The preovulatory LUTEINIZING HORMONE surge in females induces OVULATION, and subsequent LUTEINIZATION of the follicle. LUTEINIZING HORMONE consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the three pituitary glycoprotein hormones (TSH, LH and FSH), but the beta subunit is unique and confers its biological specificity. 2 0 4 6
Ligand_gated_ion_channels A subclass of ion channels that open or close in response to the binding of specific LIGANDS. 10 0 4 2
LPAR A subfamily of lysophospholipid receptors with specificity for LYSOPHOSPHATIDIC ACIDS. 3 0 0 2
LRRC8 5 1 0 1
LXR Nuclear receptors that bind OXYSTEROLS and function as heterodimers with RETINOID X RECEPTORS. They have important functions in regulating cholesterol homeostasis, ENERGY METABOLISM; INFLAMMATION; and the immune response. 2 0 5 2
MAC A product of COMPLEMENT ACTIVATION cascade, regardless of the pathways, that forms transmembrane channels causing disruption of the target CELL MEMBRANE and cell lysis. It is formed by the sequential assembly of terminal complement components (COMPLEMENT C5B; COMPLEMENT C6; COMPLEMENT C7; COMPLEMENT C8; and COMPLEMENT C9) into the target membrane. The resultant C5b-8-poly-C9 is the "membrane attack complex" or MAC. 7 0 3 6
MAC_1 An adhesion-promoting leukocyte surface membrane heterodimer. The alpha subunit consists of the CD11b ANTIGEN and the beta subunit the CD18 ANTIGEN. The antigen, which is an integrin, functions both as a receptor for complement 3 and in cell-cell and cell-substrate adhesive interactions. 2 1 1 2
Macrophage_inflammatory_proteins Heparin-binding proteins that exhibit a number of inflammatory and immunoregulatory activities. Originally identified as secretory products of MACROPHAGES, these chemokines are produced by a variety of cell types including NEUTROPHILS; FIBROBLASTS; and EPITHELIAL CELLS. They likely play a significant role in respiratory tract defenses. 2 1 0 1
MAF Maf transcription factors are a family of basic-leucine zipper transcription factors that are closely related to V-MAF ONCOGENE PROTEIN. The C-MAF PROTO-ONCOGENE PROTEIN was the first mammalian Maf transcription factor identified, and now the family is known to include a variety of other Maf proteins such as MAFB TRANSCRIPTION FACTOR; MAFF TRANSCRIPTION FACTOR; MAFG TRANSCRIPTION FACTOR; and MAFK TRANSCRIPTION FACTOR. 6 0 1 5
Microtubule_associated_proteins 8 0 4 1
MAP1 3 1 2 0
MAP1LC3 4 0 1 1
MAP2 3 1 2 0
MAP2K A serine-threonine protein kinase family whose members are components in protein kinase cascades activated by diverse stimuli. These MAPK kinases phosphorylate MITOGEN-ACTIVATED PROTEIN KINASES and are themselves phosphorylated by MAP KINASE KINASE KINASES. JNK kinases (also known as SAPK kinases) are a subfamily. 6 0 3 2
MAP3K Mitogen-activated protein kinase kinase kinases (MAPKKKs) are serine-threonine protein kinases that initiate protein kinase signaling cascades. They phosphorylate MITOGEN-ACTIVATED PROTEIN KINASE KINASES; (MAPKKs) which in turn phosphorylate MITOGEN-ACTIVATED PROTEIN KINASES; (MAPKs). 20 0 4 2
MAPK A superfamily of PROTEIN-SERINE-THREONINE KINASES that are activated by diverse stimuli via protein kinase cascades. They are the final components of the cascades, activated by phosphorylation by MITOGEN-ACTIVATED PROTEIN KINASE KINASES, which in turn are activated by mitogen-activated protein kinase kinase kinases (MAP KINASE KINASE KINASES). 3 0 8 4
MAPRE 3 1 2 1
MCM A family of proteins that were originally identified in SACCHAROMYCES CEREVISIAE as being essential for maintaining the structure of minichromosomes00. They form into a protein complex that has helicase activity and is involved in a variety of DNA-related functions including replication elongation, RNA transcription, chromatin remodeling, and genome stability. 9 0 5 7
Mechanosensitive_ion_channels 3 0 2 0
MED A large protein complex which acts as a signaling adaptor protein that allows communication between the various regulatory and functional components of GENETIC TRANSCRIPTION including DNA POLYMERASE II; GENERAL TRANSCRIPTION FACTORS; and TRANSCRIPTION FACTORS that are bound to upstream ENHANCER ELEMENTS. The mediator complex was originally studied in YEAST where at least 21 subunits were identified. Many of the yeast subunits are homologs to proteins in higher organisms that are found associated with specific nuclear receptors such as THYROID HORMONE RECEPTORS and VITAMIN D RECEPTORS. 33 0 0 1
MEF2 Activating transcription factors of the MADS family which bind a specific sequence element (MEF2 element) in many muscle-specific genes and are involved in skeletal and cardiac myogenesis, neuronal differentiation and survival/apoptosis. 4 0 2 6
MEK 2 1 3 8
Metallothionein A low-molecular-weight (approx. 10 kD) protein occurring in the cytoplasm of kidney cortex and liver. It is rich in cysteinyl residues and contains no aromatic amino acids. Metallothionein shows high affinity for bivalent heavy metals. 19 0 3 1
Methyltransferases 4 0 4 1
MGAT 9 1 1 0
MINDY 5 1 14 1
MIRLET7 2 0 1 2
MIRLET7A 3 1 1 0
MIRLET7F 2 1 1 0
Mitochondrial_Ribosome Multicomponent ribonucleoprotein structures contained in MITOCHONDRIA that specialize in the PROTEIN BIOSYNTHESIS of a small number of proteins involved in energy production for the cell. 2 0 13 2
MJD 4 1 13 1
MKNK 2 0 6 0
MMP A family of zinc-dependent metalloendopeptidases that is involved in the degradation of EXTRACELLULAR MATRIX components. 23 0 2 3
MOB 6 0 0 1
MOB1 2 1 0 1
MRC 2 1 2 0
MRN_complex The MRN complex (MRX complex in yeast) is a protein complex consisting of Mre11, Rad50 and Nbs1 (also known as Nibrin in humans and as Xrs2 in yeast). In eukaryotes, the MRN/X complex plays an important role in the initial processing of double-strand DNA breaks prior to repair by homologous recombination or non-homologous end joining. The MRN complex binds avidly to double-strand breaks both in vitro and in vivo and may serve to tether broken ends prior to repair by non-homologous end joining or to initiate resection prior to repair by homologous recombination. The MRN complex also participates in activating the checkpoint kinase ATM in response to DNA damage. Production of short single-strand oligonucleotides by Mre11 endonuclease activity has been implicated in ATM activation by the MRN complex. 4 0 2 1
MRPL 48 1 4 1
MRPS 30 1 4 2
MTNR 2 0 4 1
mTORC1 An evolutionarily conserved multiprotein complex that functions as a cellular energy sensor and regulator of protein synthesis for cell growth and proliferation. It consists of TOR SERINE-THREONINE KINASES; REGULATORY-ASSOCIATED PROTEIN OF MTOR (RAPTOR); MLST8 PROTEIN; and AKT1 substrate 1 protein. The activity of the complex is regulated by SIROLIMUS; INSULIN; GROWTH FACTORS; PHOSPHATIDIC ACIDS; some amino acids or amino acid derivatives, and OXIDATIVE STRESS. 2 0 2 6
mTORC2 A multiprotein complex consisting of MTOR KINASE; MLST8 PROTEIN; rapamycin-insensitive companion of mTOR protein (RICTOR PROTEIN); and PRR5 (proline-rich protein 5). Like MTORC1, it also regulates cell growth and proliferation in response to growth factors but may not be as sensitive to nutrient availability and is insensitive to SIROLIMUS. In contrast to MTORC1, it can regulate the ACTIN CYTOSKELETON through RHO GTPASES to promote the formation of STRESS FIBERS. The mTORC2 complex also plays a critical role in AKT1 PROTEIN KINASE phosphorylation and activation. 4 0 2 5
MYH The larger subunits of MYOSINS. The heavy chains have a molecular weight of about 230 kDa and each heavy chain is usually associated with a dissimilar pair of MYOSIN LIGHT CHAINS. The heavy chains possess actin-binding and ATPase activity. 15 1 8 3
MYL The smaller subunits of MYOSINS that bind near the head groups of MYOSIN HEAVY CHAINS. The myosin light chains have a molecular weight of about 20 KDa and there are usually one essential and one regulatory pair of light chains associated with each heavy chain. Many myosin light chains that bind calcium are considered "calmodulin-like" proteins. 3 1 4 3
MYL_alkali 5 1 4 1
MYL_regulatory 8 1 1 1
MYL_slow 3 1 1 1
MYO1 A subclass of myosins found generally associated with actin-rich membrane structures such as filopodia. Members of the myosin type I family are ubiquitously expressed in eukaryotes. The heavy chains of myosin type I lack coiled-coil forming sequences in their tails and therefore do not dimerize. 8 1 0 1
MYO15 2 1 0 0
MYO18 2 1 0 0
MYO3 A subclass of myosins originally found in the photoreceptor of DROSOPHILA. The heavy chains can occur as two alternatively spliced isoforms of 132 and 174 KDa. The amino terminal of myosin type III is highly unusual in that it contains a protein kinase domain which may be an important component of the visual process. 2 1 0 1
MYO5 A subclass of myosin involved in organelle transport and membrane targeting. It is abundantly found in nervous tissue and neurosecretory cells. The heavy chains of myosin V contain unusually long neck domains that are believed to aid in translocating molecules over large distances. 3 1 0 1
MYO7 2 1 0 0
MYO9 2 1 0 0
Myosin_complex A diverse superfamily of proteins that function as translocating proteins. They share the common characteristics of being able to bind ACTINS and hydrolyze MgATP. Myosins generally consist of heavy chains which are involved in locomotion, and light chains which are involved in regulation. Within the structure of myosin heavy chain are three domains: the head, the neck and the tail. The head region of the heavy chain contains the actin binding domain and MgATPase domain which provides energy for locomotion. The neck region is involved in binding the light-chains. The tail region provides the anchoring point that maintains the position of the heavy chain. The superfamily of myosins is organized into structural classes based upon the type and arrangement of the subunits they contain. 2 0 2 1
Myosin_family 12 1 0 0
MYST 5 0 3 2
NADH_dehydrogenase A flavoprotein and iron sulfur-containing oxidoreductase that catalyzes the oxidation of NADH to NAD. In eukaryotes the enzyme can be found as a component of mitochondrial electron transport complex I. Under experimental conditions the enzyme can use CYTOCHROME C GROUP as the reducing cofactor. The enzyme was formerly listed as EC 1.6.2.1. 7 0 2 4
NADPH_oxidase A family of membrane-associated flavoprotein NADPH-dependent oxidoreductases that catalyze the univalent reduction of OXYGEN to create SUPEROXIDES. Structurally, they are characterized by six N-terminal transmembrane ALPHA-HELICES, a FLAVIN-ADENINE DINUCLEOTIDE (FAD)-binding region, and a C-terminal NADPH-binding region. They are expressed primarily by EPITHELIAL CELLS in gut, kidney, colon, and smooth muscle tissues, as well as GRANULOCYTES and function to transfer electrons across membranes to molecular oxygen. Defects in the production of superoxide ions by some NADPH oxidases result in GRANULOMATOUS DISEASE, CHRONIC. 12 0 3 3
Na_K_ATPase An enzyme that catalyzes the active transport system of sodium and potassium ions across the cell wall. Sodium and potassium ions are closely coupled with membrane ATPase which undergoes phosphorylation and dephosphorylation, thereby providing energy for transport of these ions against concentration gradients. 2 0 5 3
Natriuretic_peptide Peptides that regulate the WATER-ELECTROLYTE BALANCE in the body, also known as natriuretic peptide hormones. Several have been sequenced (ATRIAL NATRIURETIC FACTOR; BRAIN NATRIURETIC PEPTIDE; C-TYPE NATRIURETIC PEPTIDE). 3 1 6 1
NCOA Proteins that enhance gene expression when associated with ligand bound activated NUCLEAR RECEPTORS. The coactivators may act through an enzymatic process that affects the rate of transcription or the structure of chromatin. Alternatively nuclear receptor coactivators can function as adaptor proteins that bring nuclear receptors into close proximity with transcriptional complexes. 3 0 1 6
NCOR 2 0 4 2
NDRG Ndr family 4 0 3 3
Neurexins Neurexin (NRXN) is a presynaptic protein that helps to connect neurons at the synapse. They are located mostly on the presynaptic membrane and contain a single transmembrane domain. The extracellular domain interacts with proteins in the synaptic cleft, most notably neuroligin, while the intracellular cytoplasmic portion interacts with proteins associated with exocytosis. Neurexin and neuroligin 'shake hands,' resulting in the connection between the two neurons and the production of a synapse. Neurexins mediate signaling across the synapse, and influence the properties of neural networks by synapse specificity. Neurexins were discovered as receptors for α-latrotoxin, a vertebrate-specific toxin in black widow spider venom that binds to presynaptic receptors and induces massive neurotransmitter release. In humans, alterations in genes encoding neurexins are implicated in autism and other cognitive diseases, such as Tourette syndrome and schizophrenia. 3 0 2 1
Neuropeptide_receptor Cell surface receptors that bind specific neuropeptides with high affinity and trigger intracellular changes influencing the behavior of cells. Many neuropeptides are also hormones outside of the nervous system. 4 0 2 2
Neuropeptides Peptides released by NEURONS as intercellular messengers. Many neuropeptides are also hormones released by non-neuronal cells. 63 0 2 2
Neuropilins 2 0 4 1
NFAT A family of transcription factors characterized by the presence of highly conserved calcineurin- and DNA-binding domains. NFAT proteins are activated in the CYTOPLASM by the calcium-dependent phosphatase CALCINEURIN. They transduce calcium signals to the nucleus where they can interact with TRANSCRIPTION FACTOR AP-1 or NF-KAPPA B and initiate GENETIC TRANSCRIPTION of GENES involved in CELL DIFFERENTIATION and development. NFAT proteins stimulate T-CELL activation through the induction of IMMEDIATE-EARLY GENES such as INTERLEUKIN-2. 5 0 1 4
NFE 3 0 3 2
NFkappaB Ubiquitous, inducible, nuclear transcriptional activator that binds to enhancer elements in many different cell types and is activated by pathogenic stimuli. The NF-kappa B complex is a heterodimer composed of two DNA-binding subunits: NF-kappa B1 and relA. 2 0 25 9
NFkappaB_1 2 1 16 2
NFkappaB_2 3 1 16 0
NFY A heterotrimeric DNA-binding protein that binds to CCAAT motifs in the promoters of eukaryotic genes. It is composed of three subunits: A, B and C. 3 0 4 5
NKD 2 0 1 1
NOS An NADPH-dependent enzyme that catalyzes the conversion of L-ARGININE and OXYGEN to produce CITRULLINE and NITRIC OXIDE. 3 0 1 7
Notch A family of conserved cell surface receptors that contain EPIDERMAL GROWTH FACTOR repeats in their extracellular domain and ANKYRIN REPEATS in their cytoplasmic domains. The cytoplasmic domains are released upon ligand binding and translocate to the CELL NUCLEUS, where they act as transcription factors. 4 0 2 15
NPBWR 2 1 2 1
NPFFR 2 1 2 2
NPYR Cell surface proteins that bind neuropeptide Y with high affinity and trigger intracellular changes which influence the behavior of cells. 6 1 2 2
NRG A family of peptides originally found as factors that stimulate the phosphorylation of the erbB-2 receptor (RECEPTORS, ERBB-2). Multiple variant forms of NEUREGULINS occur due to alternative splicing of their mRNAs. The NEUREGULINS include products from the three known genes (NGR1; NGR2 and NGR3). 2 0 8 5
NRG_1_2 2 1 2 4
NRG_3_4 2 1 2 1
NTRK 3 0 6 4
OGT_family 4 1 0 0
Opioid_receptor 4 0 2 1
OR Proteins, usually projecting from the cilia of olfactory receptor neurons, that specifically bind odorant molecules and trigger responses in the neurons. The large number of different odorant receptors appears to arise from several gene families or subfamilies rather than from DNA rearrangement. 17 0 2 2
OR1 30 1 0 1
OR10 38 1 0 1
OR11 9 1 0 1
OR12 3 1 0 1
OR13 13 1 0 1
OR14 6 1 0 1
OR2 68 1 0 1
OR3 3 1 0 1
OR4 55 1 0 1
OR5 50 1 0 1
OR51 24 1 0 1
OR52 27 1 0 1
OR56 6 1 0 1
OR6 30 1 0 1
OR7 11 1 0 1
OR8 26 1 0 1
OR9 9 1 0 1
OTU 7 1 0 1
OTUB 2 1 0 0
OTUD 7 1 0 0
OTUD6 2 1 0 0
OTUD7 3 1 0 0
p14_3_3 A large family of signal-transducing adaptor proteins present in wide variety of eukaryotes. They are PHOSPHOSERINE and PHOSPHOTHREONINE binding proteins involved in important cellular processes including SIGNAL TRANSDUCTION; CELL CYCLE control; APOPTOSIS; and cellular stress responses. 14-3-3 proteins function by interacting with other signal-transducing proteins and effecting changes in their enzymatic activity and subcellular localization. The name 14-3-3 derives from numerical designations used in the original fractionation patterns of the proteins. 7 0 2 10
P2R A class of cell surface receptors for PURINES that prefer ATP or ADP over ADENOSINE. P2 purinergic receptors are widespread in the periphery and in the central and peripheral nervous system. 2 1 2 1
P2RX A subclass of purinergic P2 receptors that signal by means of a ligand-gated ion channel. They are comprised of three P2X subunits which can be identical (homotrimeric form) or dissimilar (heterotrimeric form). 7 2 5 10
P2RY A subclass of purinergic P2 receptors whose signaling is coupled through a G-PROTEIN signaling mechanism. 12 1 1 3
p38 A mitogen-activated protein kinase subfamily that regulates a variety of cellular processes including CELL GROWTH PROCESSES; CELL DIFFERENTIATION; APOPTOSIS; and cellular responses to INFLAMMATION. The P38 MAP kinases are regulated by CYTOKINE RECEPTORS and can be activated in response to bacterial pathogens. 4 1 10 9
p53_family Tumor suppressor genes located on the short arm of human chromosome 17 and coding for the phosphoprotein p53. 3 0 4 8
P70S6K A family of ribosomal protein S6 kinases that are considered the major physiological kinases for RIBOSOMAL PROTEIN S6. Unlike RIBOSOMAL PROTEIN S6 KINASES, 90KDa the proteins in this family are sensitive to the inhibitory effects of RAPAMYCIN and contain a single kinase domain. They are referred to as 70kDa proteins, however ALTERNATIVE SPLICING of mRNAs for proteins in this class also results in 85kDa variants being formed. 2 1 6 3
P90RSK A family of ribosomal protein S6 kinases that are structurally distinguished from RIBOSOMAL PROTEIN S6 KINASES, 70-KDA by their apparent molecular size and the fact they contain two functional kinase domains. Although considered RIBOSOMAL PROTEIN S6 KINASES, members of this family are activated via the MAP KINASE SIGNALING SYSTEM and have been shown to act on a diverse array of substrates that are involved in cellular regulation such as RIBOSOMAL PROTEIN S6 and CAMP RESPONSE ELEMENT-BINDING PROTEIN. 6 1 2 6
PAF1_complex 6 0 1 1
PAK A family of serine-threonine kinases that bind to and are activated by MONOMERIC GTP-BINDING PROTEINS such as RAC GTP-BINDING PROTEINS and CDC42 GTP-BINDING PROTEIN. They are intracellular signaling kinases that play a role the regulation of cytoskeletal organization. 6 0 2 6
PARP Enzymes that catalyze the transfer of multiple ADP-RIBOSE groups from nicotinamide-adenine dinucleotide (NAD) onto protein targets, thus building up a linear or branched homopolymer of repeating ADP-ribose units i.e., POLY ADENOSINE DIPHOSPHATE RIBOSE. 16 0 4 2
PARV 3 0 4 3
Patched A family of 12-pass transmembrane proteins originally identified in Drosophila that are receptors for HEDGEHOG PROTEINS. They have important roles in regulating CELL PROLIFERATION; CELL DIFFERENTIAION; and BODY PATTERNING and may also function as TUMOR SUPPRESSOR PROTEINS. 2 0 2 5
PBX 4 0 4 2
PCSK 9 0 4 1
PDE A class of enzymes that catalyze the hydrolysis of one of the two ester bonds in a phosphodiester compound. EC 3.1.4. 10 0 6 3
PDE1 A CALCIUM and CALMODULIN-dependent cyclic nucleotide phosphodiesterase subfamily. The three members of this family are referred to as type 1A, type 1B, and type 1C and are each product of a distinct gene. In addition, multiple enzyme variants of each subtype can be produced due to multiple alternative mRNA splicing. Although the type 1 enzymes are classified as 3',5'-cyclic-AMP phosphodiesterases (EC 3.1.4.17), some members of this class have additional specificity for CYCLIC GMP. 3 1 6 6
PDE3 A cyclic nucleotide phosphodiesterase subfamily that is inhibited by the binding of CYCLIC GMP to an allosteric domain found on the enzyme and through phosphorylation by regulatory kinases such as PROTEIN KINASE A and PROTEIN KINASE B. The two members of this family are referred to as type 3A, and type 3B, and are each product of a distinct gene. In addition multiple enzyme variants of each subtype can be produced due to multiple alternative mRNA splicing. 2 1 7 4
PDE4 A cyclic nucleotide phosphodiesterase subfamily that is found predominantly in inflammatory cells and may play a role in the regulation of CELL-MEDIATED IMMUNITY. The enzyme family includes over twenty different variants that occur due to multiple ALTERNATIVE SPLICING of the mRNA of at least four different genes. 4 1 8 6
PDE6 A cyclic nucleotide phosphodiesterase subfamily that is highly specific for CYCLIC GMP. It is found predominantly in the outer segment PHOTORECEPTOR CELLS of the RETINA. It is comprised of two catalytic subunits, referred to as alpha and beta, that form a dimer. In addition two regulatory subunits, referred to as gamma and delta, modulate the activity and localization of the enzyme. 3 1 6 3
PDE7 A cyclic nucleotide phosphodiesterase subfamily that is highly specific for CYCLIC AMP. Several isoforms of the enzyme type exist, each with its own tissue localization. The isoforms are encoded by at least two genes and are a product of multiple alternative splicing of their mRNAs. 2 1 5 2
PDE8 2 1 5 1
PDGF Mitogenic peptide growth hormone carried in the alpha-granules of platelets. It is released when platelets adhere to traumatized tissues. Connective tissue cells near the traumatized region respond by initiating the process of replication. 4 0 1 6
PDGF_AA 1 0 3 2
PDGF_AB 2 0 3 3
PDGF_BB A recombinant human platelet-derived growth factor B-chain dimer used to promote WOUND HEALING by stimulating PHYSIOLOGIC ANGIOGENESIS. 1 0 3 15
PDGF_CC 1 0 3 1
PDGF_DD 1 0 3 1
PDGFR Specific receptors on cell membranes that react with PLATELET-DERIVED GROWTH FACTOR, its analogs, or antagonists. The alpha PDGF receptor (RECEPTOR, PLATELET-DERIVED GROWTH FACTOR ALPHA) and the beta PDGF receptor (RECEPTOR, PLATELET-DERIVED GROWTH FACTOR BETA) are the two principle types of PDGF receptors. Activation of the protein-tyrosine kinase activity of the receptors occurs by ligand-induced dimerization or heterodimerization of PDGF receptor types. 2 0 3 9
PDGFR_AA 1 0 5 3
PDGFR_AB 2 0 5 6
PDGFR_BB 1 0 5 4
PDH A multienzyme complex responsible for the formation of ACETYL COENZYME A from pyruvate. The enzyme components are PYRUVATE DEHYDROGENASE (LIPOAMIDE); dihydrolipoamide acetyltransferase; and LIPOAMIDE DEHYDROGENASE. Pyruvate dehydrogenase complex is subject to three types of control: inhibited by acetyl-CoA and NADH; influenced by the energy state of the cell; and inhibited when a specific serine residue in the pyruvate decarboxylase is phosphorylated by ATP. PYRUVATE DEHYDROGENASE (LIPOAMIDE)-PHOSPHATASE catalyzes reactivation of the complex. (From Concise Encyclopedia Biochemistry and Molecular Biology, 3rd ed) 6 0 2 2
PDK 4 0 3 4
Pertussis_toxin 0 0 3 1
PFN A family of low molecular weight proteins that bind ACTIN and control actin polymerization. They are found in eukaryotes and are ubiquitously expressed. 4 0 4 5
PhK An enzyme that catalyzes the conversion of ATP and PHOSPHORYLASE B to ADP and PHOSPHORYLASE A. 6 0 3 3
Phosphatase A group of enzymes removing the SERINE- or THREONINE-bound phosphate groups from a wide range of phosphoproteins, including a number of enzymes which have been phosphorylated under the action of a kinase. (Enzyme Nomenclature, 1992) 0 0 2 2
PI3K A phosphatidylinositol 3-kinase that catalyzes the conversion of 1-phosphatidylinositol into 1-phosphatidylinositol 3-phosphate. 2 0 16 6
PI3K_p110 4 1 3 2
PI3K_p85 2 1 1 1
PI4K An enzyme that catalyzes the conversion of phosphatidylinositol (PHOSPHATIDYLINOSITOLS) to phosphatidylinositol 4-phosphate, the first committed step in the biosynthesis of phosphatidylinositol 4,5-bisphosphate. 2 0 2 1
PIK3R_I 5 1 1 1
PIM 3 0 1 3
PKA A group of enzymes that are dependent on CYCLIC AMP and catalyze the phosphorylation of SERINE or THREONINE residues on proteins. Included under this category are two cyclic-AMP-dependent protein kinase subtypes, each of which is defined by its subunit composition. 2 0 7 3
PKC An serine-threonine protein kinase that requires the presence of physiological concentrations of CALCIUM and membrane PHOSPHOLIPIDS. The additional presence of DIACYLGLYCEROLS markedly increases its sensitivity to both calcium and phospholipids. The sensitivity of the enzyme can also be increased by PHORBOL ESTERS and it is believed that protein kinase C is the receptor protein of tumor-promoting phorbol esters. 10 0 2 6
PKI cAMP-dependent protein kinase inhibitor 3 0 1 3
PKN 3 0 0 1
PLA2 Phospholipases that hydrolyze the acyl group attached to the 2-position of PHOSPHOGLYCERIDES. 10 0 5 7
PLA2G2 5 1 5 1
PLA2G4 3 1 5 1
PLC A subclass of phospholipases that hydrolyze the phosphoester bond found in the third position of GLYCEROPHOSPHOLIPIDS. Although the singular term phospholipase C specifically refers to an enzyme that catalyzes the hydrolysis of PHOSPHATIDYLCHOLINE (EC 3.1.4.3), it is commonly used in the literature to refer to broad variety of enzymes that specifically catalyze the hydrolysis of PHOSPHATIDYLINOSITOLS. 5 0 5 2
PLCB A phosphoinositide phospholipase C subtype that is primarily regulated by its association with HETEROTRIMERIC G-PROTEINS. It is structurally related to PHOSPHOLIPASE C DELTA with the addition of C-terminal extension of 400 residues. 4 1 8 4
PLCD A phosphoinositide phospholipase C subtype that is structurally defined by the presence of an N-terminal pleckstrin-homology and EF-hand domains, a central catalytic domain, and a C-terminal calcium-dependent membrane-binding domain. 3 1 8 1
PLCG A phosphoinositide phospholipase C subtype that is primarily regulated by PROTEIN-TYROSINE KINASES. It is structurally related to PHOSPHOLIPASE C DELTA with the addition of SRC HOMOLOGY DOMAINS and pleckstrin homology domains located between two halves of the CATALYTIC DOMAIN. 2 1 2 11
PLD An enzyme found mostly in plant tissue. It hydrolyzes glycerophosphatidates with the formation of a phosphatidic acid and a nitrogenous base such as choline. This enzyme also catalyzes transphosphatidylation reactions. EC 3.1.4.4. 6 0 2 4
PLOD 3 0 0 1
Pocket_protein 3 0 6 0
Porins Porins are protein molecules that were originally found in the outer membrane of GRAM-NEGATIVE BACTERIA and that form multi-meric channels for the passive DIFFUSION of WATER; IONS; or other small molecules. Porins are present in bacterial CELL WALLS, as well as in plant, fungal, mammalian and other vertebrate CELL MEMBRANES and MITOCHONDRIAL MEMBRANES. 2 0 3 2
Potassium_calcium_activated_channels Potassium channels whose activation is dependent on intracellular calcium concentrations. 6 2 0 2
Potassium_voltage_gated_channels Potassium channel whose permeability to ions is extremely sensitive to the transmembrane potential difference. The opening of these channels is induced by the membrane depolarization of the ACTION POTENTIAL. 33 2 0 2
PPAP2 3 0 4 3
PPAR TRANSCRIPTION FACTORS that are activated by ligands and heterodimerize with RETINOID X RECEPTORS and bind to peroxisome proliferator response elements in the promoter regions of target genes. 3 0 1 4
PPP1 A eukayrotic protein serine-threonine phosphatase subtype that dephosphorylates a wide variety of cellular proteins. The enzyme is comprised of a catalytic subunit and regulatory subunit. Several isoforms of the protein phosphatase catalytic subunit exist due to the presence of multiple genes and the alternative splicing of their mRNAs. A large number of proteins have been shown to act as regulatory subunits for this enzyme. Many of the regulatory subunits have additional cellular functions. 2 0 4 5
PPP1C 3 1 3 3
PPP1R 27 1 2 1
PPP2 A phosphoprotein phosphatase subtype that is comprised of a catalytic subunit and two different regulatory subunits. At least two genes encode isoforms of the protein phosphatase catalytic subunit, while several isoforms of regulatory subunits exist due to the presence of multiple genes and the alternative splicing of their mRNAs. Protein phosphatase 2 acts on a broad variety of cellular proteins and may play a role as a regulator of intracellular signaling processes. 3 0 5 4
PPP2C One of four major classes of mammalian serine/threonine specific protein phosphatases. Protein phosphatase 2C is a monomeric enzyme about 42 kDa in size. It shows broad substrate specificity dependent on divalent cations (mainly manganese and magnesium). Three isozymes are known in mammals: PP2C -alpha, -beta and -gamma. In yeast, there are four PP2C homologues: phosphatase PTC1 that have weak tyrosine phosphatase activity, phosphatase PTC2, phosphatase PTC3, and PTC4. Isozymes of PP2C also occur in Arabidopsis thaliana where the kinase-associated protein phosphatase (KAPP) containing a C-terminal PP2C domain, dephosphorylates Ser/Thr receptor-like kinase RLK5. 3 1 3 2
PPP2R_A 2 1 2 3
PPP2R_B 12 1 2 1
PPP3 A CALCIUM and CALMODULIN-dependent serine/threonine protein phosphatase that is composed of the calcineurin A catalytic subunit and the calcineurin B regulatory subunit. Calcineurin has been shown to dephosphorylate a number of phosphoproteins including HISTONES; MYOSIN LIGHT CHAIN; and the regulatory subunits of CAMP-DEPENDENT PROTEIN KINASES. It is involved in the regulation of signal transduction and is the target of an important class of immunophilin-immunosuppressive drug complexes. 2 0 4 4
PPP3C 3 1 3 4
PPP3R 2 1 2 2
PRC1_complex A multisubunit polycomb protein complex with affinity for CHROMATIN that contains methylated HISTONE H3. It contains an E3 ubiquitin ligase activity that is specific for HISTONE H2A and works in conjunction with POLYCOMB REPRESSIVE COMPLEX 2 to effect EPIGENETIC REPRESSION. 14 0 7 5
PRC2_complex A multisubunit polycomb protein complex that catalyzes the METHYLATION of chromosomal HISTONE H3. It works in conjunction with POLYCOMB REPRESSIVE COMPLEX 1 to effect EPIGENETIC REPRESSION. 4 0 7 4
PRDUB_complex 2 1 0 2
PRDX A family of ubiquitously-expressed peroxidases that play a role in the reduction of a broad spectrum of PEROXIDES like HYDROGEN PEROXIDE; LIPID PEROXIDES and peroxinitrite. They are found in a wide range of organisms, such as BACTERIA; PLANTS; and MAMMALS. The enzyme requires the presence of a thiol-containing intermediate such as THIOREDOXIN as a reducing cofactor. 6 0 5 3
PRKAC 3 1 8 2
PRKAR 4 1 7 6
PRKG A group of cyclic GMP-dependent enzymes that catalyze the phosphorylation of SERINE or THREONINE residues of proteins. 2 0 2 8
PRMT 9 1 0 1
Propionyl_CoA_carboxylase 2 0 2 9
Protease Hydrolases that specifically cleave the peptide bonds found in PROTEINS and PEPTIDES. Examples of sub-subclasses for this group include EXOPEPTIDASES and ENDOPEPTIDASES. 0 0 8 2
Proteasome A large multisubunit complex that plays an important role in the degradation of most of the cytosolic and nuclear proteins in eukaryotic cells. It contains a 700-kDa catalytic sub-complex and two 700-kDa regulatory sub-complexes. The complex digests ubiquitinated proteins and protein activated via ornithine decarboxylase antizyme. 44 0 2 4
PTGER Cell surface receptors which bind prostaglandins with a high affinity and trigger intracellular changes which influence the behavior of cells. Prostaglandin E receptors prefer prostaglandin E2 to other endogenous prostaglandins. They are subdivided into EP1, EP2, and EP3 types based on their effects and their pharmacology. 4 0 1 2
Purinergic_receptors Cell surface proteins that bind PURINES with high affinity and trigger intracellular changes which influence the behavior of cells. The best characterized classes of purinergic receptors in mammals are the P1 receptors, which prefer ADENOSINE, and the P2 receptors, which prefer ATP or ADP. 2 0 3 1
PYG An enzyme that catalyzes the degradation of GLYCOGEN in animals by releasing glucose-1-phosphate from the terminal alpha-1,4-glycosidic bond. This enzyme exists in two forms: an active phosphorylated form ( PHOSPHORYLASE A) and an inactive un-phosphorylated form (PHOSPHORYLASE B). Both a and b forms of phosphorylase exist as homodimers. In mammals, the major isozymes of glycogen phosphorylase are found in muscle, liver and brain tissue. 3 1 5 1
RAB A large family of MONOMERIC GTP-BINDING PROTEINS that play a key role in cellular secretory and endocytic pathways. 68 0 8 4
RAC A sub-family of RHO GTP-BINDING PROTEINS that is involved in regulating the organization of cytoskeletal filaments. This enzyme was formerly listed as EC 3.6.1.47. 4 0 3 3
RAF A family of closely-related serine-threonine kinases that were originally identified as the cellular homologs of the retrovirus-derived V-RAF KINASES. They are MAP kinase kinase kinases that play important roles in SIGNAL TRANSDUCTION. 3 1 3 7
RAL 2 0 6 3
RAP1 2 0 1 1
RAPGEF 2 0 3 0
RAR Proteins in the nucleus or cytoplasm that specifically bind RETINOIC ACID or RETINOL and trigger changes in the behavior of cells. Retinoic acid receptors, like steroid receptors, are ligand-activated transcription regulators. Several types have been recognized. 3 0 2 4
RAS Small, monomeric GTP-binding proteins encoded by ras genes (GENES, RAS). The protooncogene-derived protein, PROTO-ONCOGENE PROTEIN P21(RAS), plays a role in normal cellular growth, differentiation and development. The oncogene-derived protein (ONCOGENE PROTEIN P21(RAS)) can play a role in aberrant cellular regulation during neoplastic cell transformation (CELL TRANSFORMATION, NEOPLASTIC). This enzyme was formerly listed as EC 3.6.1.47. 3 0 3 13
RASA 3 0 1 0
RASAL 3 0 1 0
RasGAP PROTEINS that specifically activate the GTP-phosphohydrolase activity of RAS PROTEINS. 0 0 2 3
RASGRF A family of GUANINE NUCLEOTIDE EXCHANGE FACTORS that are specific for RAS PROTEINS. 2 0 1 2
RASGRP 4 0 1 1
RASSF 10 0 5 1
RFC A DNA-binding protein and AAA ATPase that consists of 5 polypeptides and plays an essential role in DNA REPLICATION in eukaryotes. It binds DNA PRIMER-template junctions and recruits PROLIFERATING CELL NUCLEAR ANTIGEN and DNA POLYMERASES to the site of DNA synthesis. 5 0 5 6
RFX A family of eukaryotic transcription factors that recognize and bind to a highly-conserved cis-regulatory sequence (X-box) within the promoter region of MHC CLASS II GENES. They contain a conserved winged-helix DNA binding domain and function as homo or heterodimers. 8 0 5 3
RGL 3 0 4 0
RHO A large family of MONOMERIC GTP-BINDING PROTEINS that are involved in regulation of actin organization, gene expression and cell cycle progression. This enzyme was formerly listed as EC 3.6.1.47. 3 0 2 7
RhoGDI A subcategory of guanine nucleotide dissociation inhibitors that are specific for RHO GTP-BINDING PROTEINS. 3 0 5 3
RIPK A family of serine-threonine kinases that plays a role in intracellular signal transduction by interacting with a variety of signaling adaptor proteins such as CRADD SIGNALING ADAPTOR PROTEIN; TNF RECEPTOR-ASSOCIATED FACTOR 2; and TNF RECEPTOR-ASSOCIATED DEATH DOMAIN PROTEIN. Although they were initially described as death domain-binding adaptor proteins, members of this family may contain other protein-binding domains such as those involving caspase activation and recruitment. 2 0 1 1
RLR 3 0 3 0
RNApo_I A DNA-dependent RNA polymerase present in bacterial, plant, and animal cells. The enzyme functions in the nucleolar structure and transcribes DNA into RNA. It has different requirements for cations and salts than RNA polymerase II and III and is not inhibited by alpha-amanitin. 4 0 3 4
RNApo_II A DNA-dependent RNA polymerase present in bacterial, plant, and animal cells. It functions in the nucleoplasmic structure and transcribes DNA into RNA. It has different requirements for cations and salt than RNA polymerase I and is strongly inhibited by alpha-amanitin. EC 2.7.7.6. 13 0 2 5
ROBO 3 0 0 1
ROCK A group of intracellular-signaling serine threonine kinases that bind to RHO GTP-BINDING PROTEINS. They were originally found to mediate the effects of rhoA GTP-BINDING PROTEIN on the formation of STRESS FIBERS and FOCAL ADHESIONS. Rho-associated kinases have specificity for a variety of substrates including MYOSIN-LIGHT-CHAIN PHOSPHATASE and LIM KINASES. 2 0 2 6
ROR A family of cell surface receptors that were originally identified by their structural homology to neurotropic TYROSINE KINASES and referred to as orphan receptors because the associated ligand and signaling pathways were unknown. Evidence for the functionality of these proteins has been established by experiments showing that disruption of the orphan receptor genes results in developmental defects. 2 0 4 5
RPA A single-stranded DNA-binding protein that is found in EUKARYOTIC CELLS. It is required for DNA REPLICATION; DNA REPAIR; and GENETIC RECOMBINATION. 3 0 3 2
RSK A family of protein serine/threonine kinases which act as intracellular signalling intermediates. Ribosomal protein S6 kinases are activated through phosphorylation in response to a variety of HORMONES and INTERCELLULAR SIGNALING PEPTIDES AND PROTEINS. Phosphorylation of RIBOSOMAL PROTEIN S6 by enzymes in this class results in increased expression of 5' top MRNAs. Although specific for RIBOSOMAL PROTEIN S6 members of this class of kinases can act on a number of substrates within the cell. The immunosuppressant SIROLIMUS inhibits the activation of ribosomal protein S6 kinases. 2 0 1 1
RSTK 2 0 0 0
RSTK1 7 1 0 0
RSTK2 5 1 0 0
RTK 0 0 1 1
RXR A subtype of RETINOIC ACID RECEPTORS that are specific for 9-cis-retinoic acid which function as nuclear TRANSCRIPTION FACTORS that regulate multiple signaling pathways. 3 0 3 6
RYR A tetrameric calcium release channel in the SARCOPLASMIC RETICULUM membrane of SMOOTH MUSCLE CELLS, acting oppositely to SARCOPLASMIC RETICULUM CALCIUM-TRANSPORTING ATPASES. It is important in skeletal and cardiac excitation-contraction coupling and studied by using RYANODINE. Abnormalities are implicated in CARDIAC ARRHYTHMIAS and MUSCULAR DISEASES. 3 2 0 2
S100 A family of highly acidic calcium-binding proteins found in large concentration in the brain and believed to be glial in origin. They are also found in other organs in the body. They have in common the EF-hand motif (EF HAND MOTIFS) found on a number of calcium binding proteins. The name of this family derives from the property of being soluble in a 100% saturated ammonium sulfate solution. 5 0 1 1
S100A 18 1 2 1
S1PR 5 0 4 6
SAA An ACUTE PHASE REACTION protein present in low concentrations in normal sera, but found at higher concentrations in sera of older persons and in patients with AMYLOIDOSIS. It is the circulating precusor of amyloid A protein, which is found deposited in AA type AMYLOID FIBRILS. 3 0 1 5
Sarcoglycan_complex A family of transmembrane dystrophin-associated proteins that play a role in the membrane association of the DYSTROPHIN-ASSOCIATED PROTEIN COMPLEX. 5 1 4 1
SCAR 27 0 4 1
SCD 2 0 3 4
SCN A family of membrane proteins that selectively conduct SODIUM ions due to changes in the TRANSMEMBRANE POTENTIAL DIFFERENCE. They typically have a multimeric structure with a core alpha subunit that defines the sodium channel subtype and several beta subunits that modulate sodium channel activity. 2 2 0 2
SCNN Sodium channels found on salt-reabsorbing EPITHELIAL CELLS that line the distal NEPHRON; the distal COLON; SALIVARY DUCTS; SWEAT GLANDS; and the LUNG. They are AMILORIDE-sensitive and play a critical role in the control of sodium balance, BLOOD VOLUME, and BLOOD PRESSURE. 4 1 0 2
SENP 7 1 8 1
SERCA Calcium-transporting ATPases that catalyze the active transport of CALCIUM into the SARCOPLASMIC RETICULUM vesicles from the CYTOPLASM. They are primarily found in MUSCLE CELLS and play a role in the relaxation of MUSCLES. 3 0 4 6
SERPINB 13 0 3 2
SGC A mammalian enzyme composed of a heterodimer of alpha and beta subunits. Each subunit consists of four domains; N-terminal HNOX domain, PAS-like domain, a coiled-coil domain, and a C-terminal catalytic domain. All four domains are homologous proteins with a similar conformation of functional domains. Soluble guanylate cyclase catalyzes the formation of cyclic GMP from GTP, and is a key enzyme of the nitric oxide signaling pathway involved in the regulation of a variety of biological and physiological processes in mammals. 2 0 4 1
SHC A family of signaling adaptor proteins that contain SRC HOMOLOGY DOMAINS. Many members of this family are involved in transmitting signals from CELL SURFACE RECEPTORS to MITOGEN-ACTIVATED PROTEIN KINASES. 4 0 3 4
SIK 3 0 2 0
SLC2A A family of monosaccharide transport proteins characterized by 12 membrane spanning helices. They facilitate passive diffusion of GLUCOSE across the CELL MEMBRANE. 13 0 4 4
SLRP A proteoglycan family (SLRPs) that is defined by a central domain which consists of a variable number of repeats of the motif LXXLxLXXNxL, where L may be LEUCINE; ISOLEUCINE; VALINE; or other hydrophobic amino acids. The N-terminal contains four conserved CYSTEINE residues and may be modified depending on function. SLRPs provide structural support to the EXTRACELLULAR MATRIX and are critical for regulating its assembly and dynamics at CELL-MATRIX JUNCTIONS. 5 0 10 3
SLRP_1 4 1 0 1
SLRP_2 5 1 0 1
SLRP_3 3 1 0 1
SLRP_4 3 1 0 1
SLRP_5 2 1 0 1
SMAD A family of proteins that are involved in the translocation of signals from TGF-BETA RECEPTORS; BONE MORPHOGENETIC PROTEIN RECEPTORS; and other surface receptors to the CELL NUCLEUS. They were originally identified as a class of proteins that are related to the mothers against decapentaplegic protein, Drosophila and sma proteins from CAENORHABDITIS ELEGANS. 8 0 3 7
SMAD1_5_9 3 1 0 1
SMAD2_3 2 1 3 7
SMC1 2 0 2 2
SMURF 2 0 0 1
SNAI A transcription factor family characterized by the presence of several C-terminal CYS2-HIS2 ZINC FINGERS. They function in many developmental processes including the induction of the EPITHELIAL-MESENCHYMAL TRANSITION; maintenance of embryonic MESODERM; growth arrest, CELL SURVIVAL; and CELL MIGRATION. 3 0 2 2
SOD An oxidoreductase that catalyzes the reaction between SUPEROXIDES and hydrogen to yield molecular oxygen and hydrogen peroxide. The enzyme protects the cell against dangerous levels of superoxide. 3 0 1 2
Sodium_channels Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function. 4 1 4 2
Sodium_voltage_gated_channel_alpha_subunits Sodium channels are voltage-gated sodium-selective ion channels present in the membrane of most excitable cells. Sodium channels comprise of one pore-forming α subunit, which may be associated with either one or two beta subunits. Alpha-subunits consist of four homologous domains (I–IV), each containing six transmembrane segments (S1–S6) and a pore-forming loop. The positively charged fourth transmembrane segment (S4) acts as a voltage sensor and is involved in channel gating. 9 1 0 1
Sodium_voltage_gated_channel_beta_subunits Voltage-gated sodium channel subunits that play a role in the assembly, expression, and functional modulation of the sodium channel. They form a heterotrimeric complex with the pore-forming sodium channel alpha subunits. 4 1 0 2
SOS A class of RAS GUANINE NUCLEOTIDE EXCHANGE FACTORS that are genetically related to the Son of Sevenless gene from DROSOPHILA. Sevenless refers to genetic mutations in DROSOPHILA that cause loss of the R7 photoreceptor which is required to see UV light. 2 0 1 3
SP 9 0 1 1
SPHK 2 0 3 1
SPRED 3 0 1 2
SPRY 4 0 1 0
SRC A PROTEIN-TYROSINE KINASE family that was originally identified by homology to the Rous sarcoma virus ONCOGENE PROTEIN PP60(V-SRC). They interact with a variety of cell-surface receptors and participate in intracellular signal transduction pathways. Oncogenic forms of src-family kinases can occur through altered regulation or expression of the endogenous protein and by virally encoded src (v-src) genes. 4 0 7 5
SREBF Sterol regulatory element binding proteins are basic helix-loop-helix leucine zipper transcription factors that bind the sterol regulatory element TCACNCCAC. They are synthesized as precursors that are threaded into the MEMBRANES of the ENDOPLASMIC RETICULUM. 2 0 4 9
STAT A family of transcription factors containing SH2 DOMAINS that are involved in CYTOKINE-mediated SIGNAL TRANSDUCTION. STAT transcription factors are recruited to the cytoplasmic region of CELL SURFACE RECEPTORS and are activated via PHOSPHORYLATION. Once activated they dimerize and translocate into the CELL NUCLEUS where they influence GENE expression. They play a role in regulating CELL GROWTH PROCESSES and CELL DIFFERENTIATION. STAT transcription factors are inhibited by SUPPRESSOR OF CYTOKINE SIGNALING PROTEINS and PROTEIN INHIBITORS OF ACTIVATED STAT. 6 0 2 11
STAT5 A signal transducer and activator of transcription that mediates cellular responses to a variety of CYTOKINES. Stat5 activation is associated with transcription of CELL CYCLE regulators such as CYCLIN KINASE INHIBITOR P21 and anti-apoptotic genes such as BCL-2 GENES. Stat5 is constitutively activated in many patients with acute MYELOID LEUKEMIA. 2 1 2 9
STT3 2 1 1 0
Sulfonylurea_receptor ATP-BINDING CASSETTE PROTEINS that are highly conserved and widely expressed in nature. They form an integral part of the ATP-sensitive potassium channel complex which has two intracellular nucleotide folds that bind to sulfonylureas and their analogs. 2 0 4 4
SWI_SNF 16 0 4 5
TAB 3 0 4 0
TAC 3 1 0 1
TAOK 3 1 0 1
TAP A subfamily of transmembrane proteins from the superfamily of ATP-BINDING CASSETTE TRANSPORTERS that are closely related in sequence to ATP BINDING CASSETTE TRANSPORTER, SUBFAMILY B, MEMBER 1. When overexpressed, they function as ATP-dependent efflux pumps able to extrude lipophilic drugs, especially ANTINEOPLASTIC AGENTS, from cells causing multidrug resistance (DRUG RESISTANCE, MULTIPLE). Although ATP BINDING CASSETTE TRANSPORTER, SUBFAMILY B share functional similarities to MULTIDRUG RESISTANCE-ASSOCIATED PROTEINS they are two distinct subclasses of ATP-BINDING CASSETTE TRANSPORTERS, and have little sequence homology. 3 0 2 3
TAT_associated_kinase A transcriptional elongation factor complex that is comprised of a heterodimer of CYCLIN-DEPENDENT KINASE 9 and one of several CYCLINS including TYPE T CYCLINS and cyclin K. It functions by phosphorylating the carboxy-terminal domain of RNA POLYMERASE II. 2 0 0 1
TCF_LEF A family of DNA-binding proteins that are primarily expressed in T-LYMPHOCYTES. They interact with BETA CATENIN and serve as transcriptional activators and repressors in a variety of developmental processes. 4 0 4 9
TCR Molecules on the surface of T-lymphocytes that recognize and combine with antigens. The receptors are non-covalently associated with a complex of several polypeptides collectively called CD3 antigens (CD3 COMPLEX). Recognition of foreign antigen and the major histocompatibility complex is accomplished by a single heterodimeric antigen-receptor structure, composed of either alpha-beta (RECEPTORS, ANTIGEN, T-CELL, ALPHA-BETA) or gamma-delta (RECEPTORS, ANTIGEN, T-CELL, GAMMA-DELTA) chains. 4 0 2 2
TEAD 4 0 2 1
TFAP2 A family of DNA binding proteins that regulate expression of a variety of GENES during CELL DIFFERENTIATION and APOPTOSIS. Family members contain a highly conserved carboxy-terminal basic HELIX-TURN-HELIX MOTIF involved in dimerization and sequence-specific DNA binding. 5 0 3 7
TFDP 2 0 3 2
TGFB A factor synthesized in a wide variety of tissues. It acts synergistically with TGF-alpha in inducing phenotypic transformation and can also act as a negative autocrine growth factor. TGF-beta has a potential role in embryonal development, cellular differentiation, hormone secretion, and immune function. TGF-beta is found mostly as homodimer forms of separate gene products TGF-beta1, TGF-beta2 or TGF-beta3. Heterodimers composed of TGF-beta1 and 2 (TGF-beta1.2) or of TGF-beta2 and 3 (TGF-beta2.3) have been isolated. The TGF-beta proteins are synthesized as precursor proteins. 3 0 14 9
TGFBR Cell-surface proteins that bind transforming growth factor beta and trigger changes influencing the behavior of cells. Two types of transforming growth factor receptors have been recognized. They differ in affinity for different members of the transforming growth factor beta family and in cellular mechanisms of action. 3 0 10 3
TGM 9 0 4 1
THBS A family of related, adhesive glycoproteins which are synthesized, secreted, and incorporated into the extracellular matrix of a variety of cells, including alpha granules of platelets following thrombin activation and endothelial cells. They interact with a number of BLOOD COAGULATION FACTORS and anticoagulant factors. Five distinct forms have been identified, thrombospondin 1, -2, -3, -4, and cartilage oligomeric matrix protein (COMP). They are involved in cell adhesion, platelet aggregation, cell proliferation, angiogenesis, tumor metastasis, VASCULAR SMOOTH MUSCLE growth, and tissue repair. 5 0 5 7
THR Specific high affinity binding proteins for THYROID HORMONES in target cells. They are usually found in the nucleus and regulate DNA transcription. These receptors are activated by hormones that leads to transcription, cell differentiation, and growth suppression. Thyroid hormone receptors are encoded by two genes (GENES, ERBA): erbA-alpha and erbA-beta for alpha and beta thyroid hormone receptors, respectively. 2 0 1 3
Thrombin_antithrombin 2 0 1 5
TIAM 2 0 1 1
TIF_IB 4 0 1 2
TIM22_complex 6 0 2 2
TK An enzyme that catalyzes the conversion of ATP and thymidine to ADP and thymidine 5'-phosphate. Deoxyuridine can also act as an acceptor and dGTP as a donor. (From Enzyme Nomenclature, 1992) EC 2.7.1.21. 2 1 1 1
TLR A family of pattern recognition receptors characterized by an extracellular leucine-rich domain and a cytoplasmic domain that share homology with the INTERLEUKIN 1 RECEPTOR and the DROSOPHILA toll protein. Following pathogen recognition, toll-like receptors recruit and activate a variety of SIGNAL TRANSDUCING ADAPTOR PROTEINS. 10 0 1 3
TN Hexameric extracellular matrix glycoprotein transiently expressed in many developing organs and often re-expressed in tumors. It is present in the central and peripheral nervous systems as well as in smooth muscle and tendons. (From Kreis & Vale, Guidebook to the Extracellular Matrix and Adhesion Proteins, 1993, p93) 4 0 2 6
TNF TNF(Tumour Necrosis Factor) family 0 0 0 2
TNFRSF Cell surface receptors that bind TUMOR NECROSIS FACTORS and trigger changes which influence the behavior of cells. 20 0 8 3
TOP Enzymes that regulate the topology of DNA by actions such as breaking, relaxing, passing, and rejoining strands of DNA in cells. These enzymes are important components of the DNA replication system. They are classified by their substrate specificities. DNA TOPOISOMERASE I enzymes act on a single strand of DNA. DNA TOPOISOMERASE II enzymes act on double strands of DNA. 5 0 1 2
TOP2 DNA TOPOISOMERASES that catalyze ATP-dependent breakage of both strands of DNA, passage of the unbroken strands through the breaks, and rejoining of the broken strands. These enzymes bring about relaxation of the supercoiled DNA and resolution of a knotted circular DNA duplex. 2 1 1 16
TPCN This small family of 2 members putatively forms cation-selective ion channels. They are predicted to contain two KV-style six-transmembrane domains, suggesting they form a dimer in the membrane. These channels are closely related to CatSper channels and, more distantly, to TRP channels. 2 2 0 1
TRAF Intracellular signaling peptides and proteins that bind directly or indirectly to the cytoplasmic portion of TUMOR NECROSIS FACTOR RECEPTORS. 7 0 6 2
TRMT 18 1 0 2
Troponin One of the minor protein components of skeletal and cardiac muscles. It functions as the calcium-binding component in a complex with BETA-TROPOMYOSIN; ACTIN; and MYOSIN and confers calcium sensitivity to the cross-linked actin and myosin filaments. Troponin itself is a complex of three regulatory proteins (TROPONIN C; TROPONIN I; and TROPONIN T). 3 0 3 5
Troponin_C A TROPONIN complex subunit that binds calcium and help regulate calcium-dependent muscle contraction. There are two troponin C subtypes: troponin C1 and C2. Troponin C1 is skeletal and cardiac type whereas troponin C2 is skeletal type. Troponin C1 is a BIOMARKER for damaged or injured CARDIAC MYOCYTES and mutations in troponin C1 gene are associated with FAMILIAL HYPERTROPHIC CARDIOMYOPATHY. 2 1 4 3
Troponin_I A TROPONIN complex subunit that inhibits ACTOMYOSIN ATPASE activity thereby disrupting ACTIN and MYOSIN interaction. There are three troponin I subtypes: troponin I1, I2 and I3. Troponin I3 is cardiac-specific whereas troponin I1 and I2 are skeletal subtypes. Troponin I3 is a BIOMARKER for damaged or injured CARDIAC MYOCYTES and mutations in troponin I3 gene are associated with FAMILIAL HYPERTROPHIC CARDIOMYOPATHY. 3 1 3 3
Troponin_T A TROPONIN complex subunit that binds to TROPOMYOSIN. There are three troponin T subtypes: troponin T1, T2 and T3. Troponin T2 is cardiac-specific whereas troponin T2 and T3 are skeletal subtypes. Troponin T2 is a BIOMARKER for damaged or injured CARDIAC MYOCYTES and mutations in troponin T2 gene are associated with FAMILIAL HYPERTROPHIC CARDIOMYOPATHY. 3 1 3 4
TRP A broad group of eukaryotic six-transmembrane cation channels that are classified by sequence homology because their functional involvement with SENSATION is varied. They have only weak voltage sensitivity and ion selectivity. They are named after a DROSOPHILA mutant that displayed transient receptor potentials in response to light. A 25-amino-acid motif containing a TRP box (EWKFAR) just C-terminal to S6 is found in TRPC, TRPV and TRPM subgroups. ANKYRIN REPEATS are found in TRPC, TRPV & TRPN subgroups. Some are functionally associated with TYROSINE KINASE or TYPE C PHOSPHOLIPASES. 28 2 0 2
Tryptase A family of neutral serine proteases with TRYPSIN-like activity. Tryptases are primarily found in the SECRETORY GRANULES of MAST CELLS and are released during mast cell degranulation. 4 0 3 5
TSC 2 0 1 4
TUBA 9 1 5 1
TUBB 8 1 13 3
TUBG 2 1 7 2
Tubulin A microtubule subunit protein found in large quantities in mammalian brain. It has also been isolated from SPERM FLAGELLUM; CILIA; and other sources. Structurally, the protein is a dimer with a molecular weight of approximately 120,000 and a sedimentation coefficient of 5.8S. It binds to COLCHICINE; VINCRISTINE; and VINBLASTINE. 5 0 1 6
TXN Hydrogen-donating proteins that participates in a variety of biochemical reactions including ribonucleotide reduction and reduction of PEROXIREDOXINS. Thioredoxin is oxidized from a dithiol to a disulfide when acting as a reducing cofactor. The disulfide form is then reduced by NADPH in a reaction catalyzed by THIOREDOXIN REDUCTASE. 2 0 3 4
TXNRD A FLAVOPROTEIN enzyme that catalyzes the oxidation of THIOREDOXINS to thioredoxin disulfide in the presence of NADP+. It was formerly listed as EC 1.6.4.5 3 0 2 3
UBE2 A class of enzymes that form a thioester bond to UBIQUITIN with the assistance of UBIQUITIN-ACTIVATING ENZYMES. They transfer ubiquitin to the LYSINE of a substrate protein with the assistance of UBIQUITIN-PROTEIN LIGASES. 29 0 5 5
Ubiquitin A highly conserved 76-amino acid peptide universally found in eukaryotic cells that functions as a marker for intracellular PROTEIN TRANSPORT and degradation. Ubiquitin becomes activated through a series of complicated steps and forms an isopeptide bond to lysine residues of specific proteins within the cell. These "ubiquitinated" proteins can be recognized and degraded by proteosomes or be transported to specific compartments within the cell. 0 0 4 5
UCHL 4 1 23 1
UGGT 2 1 0 0
UGT 32 1 1 0
USP 54 1 0 1
USPL 2 2 0 1
USP9 2 1 0 0
USP17L 2 1 0 0
VAV Proteins that are guanine nucleotide exchange factors for RHO GTPASES. They contain pleckstrin homology and SH2 domains, through which they function as signal transducing adaptor proteins. 3 0 2 10
VDAC A family of voltage-gated eukaryotic porins that form aqueous channels. They play an essential role in mitochondrial CELL MEMBRANE PERMEABILITY, are often regulated by BCL-2 PROTO-ONCOGENE PROTEINS, and have been implicated in APOPTOSIS. 3 1 0 2
VEGF A family of angiogenic proteins that are closely-related to VASCULAR ENDOTHELIAL GROWTH FACTOR A. They play an important role in the growth and differentiation of vascular as well as lymphatic endothelial cells. 5 0 2 5
VEGFR A family of closely related RECEPTOR PROTEIN-TYROSINE KINASES that bind vascular endothelial growth factors. They share a cluster of seven extracellular IG-LIKE DOMAINS which are important for ligand binding. They are highly expressed in vascular endothelial cells and are critical for the physiological and pathological growth, development and maintenance of blood and lymphatic vessels. 3 0 4 4
Voltage_gated_ion_channels Voltage-gated ion channels are a class of transmembrane ion channels that are activated by changes in electrical membrane potential near the channel; these types of ion channels are especially critical in neurons, but are common in many types of cells. They have a crucial role in excitable neuronal and muscle tissues, allowing a rapid and co-ordinated depolarization in response to triggering voltage change. Found along the axon and at the synapse, voltage-gated ion channels directionally propagate electrical signals. 10 0 2 1
VTNR An integrin that binds to a variety of plasma and extracellular matrix proteins containing the conserved RGD amino acid sequence and modulates cell adhesion. Integrin alphavbeta3 is highly expressed in OSTEOCLASTS where it may play role in BONE RESORPTION. It is also abundant in vascular smooth muscle and endothelial cells, and in some tumor cells, where it is involved in angiogenesis and cell migration. Although often referred to as the vitronectin receptor there is more than one receptor for vitronectin (RECEPTORS, VITRONECTIN). 2 1 5 1
Wnt Wnt proteins are a large family of secreted glycoproteins that play essential roles in EMBRYONIC AND FETAL DEVELOPMENT, and tissue maintenance. They bind to FRIZZLED RECEPTORS and act as PARACRINE PROTEIN FACTORS to initiate a variety of SIGNAL TRANSDUCTION PATHWAYS. The canonical Wnt signaling pathway stabilizes the transcriptional coactivator BETA CATENIN. 18 0 2 13
Wnt5 2 1 3 0
YBX 3 0 3 0