receptors, adrenergicmedical dictionary

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.

(12 Dec 1998)

receptors, adrenergic, alphamedical dictionary

One of the two major pharmacological subdivisions of adrenergic receptors. The alpha-beta distinction was originally based on cellular effects of receptor activation but now relies on the relative affinities for certain synthetic ligands. Alpha-adrenergic receptors are further subdivided into several subclasses based on studies of endogenous and cloned receptors.

(12 Dec 1998)

receptors, adrenergic, alpha-1medical dictionary

A subclass of alpha-adrenergic receptors (receptors, adrenergic, alpha). Alpha-1 adrenergic receptors can be pharmacologically discriminated, e.g., by their high affinity for the agonist phenylephrine and the antagonist prazosin. They are widespread, with clinically important concentrations in the liver, the heart, vascular, intestinal, and genitourinary smooth muscle, and the central and peripheral nervous systems.

(12 Dec 1998)

receptors, adrenergic, alpha-2medical dictionary

A subclass of alpha-adrenergic receptors (receptors, adrenergic, alpha). Alpha-2 adrenergic receptors can be pharmacologically discriminated, e.g., by their high affinity for the agonist clonidine and the antagonist yohimbine. They are found on pancreatic beta cells, platelets, and vascular smooth muscle, as well as both pre- and postsynaptically in the central and peripheral nervous systems.

(12 Dec 1998)

receptors, adrenergic, betamedical dictionary

One of the two major pharmacologically defined classes of adrenergic receptors. The alpha-beta distinction was originally based on the cellular effects of receptor activation but now relies on the relative affinities for characteristic synthetic ligands. Beta adrenergic receptors are further subdivided based on information from endogenous and cloned receptors.

(12 Dec 1998)

receptors, adrenergic, beta-1medical dictionary
receptors, adrenergic, beta-2medical dictionary

A subclass of beta-adrenergic receptors (receptors, adrenergic, beta). Beta-2 adrenergic receptors are more sensitive to epinephrine than to norepinephrine and have a high affinity for the agonist terbutaline. They are widespread, with clinically important roles in skeletal muscle, liver, and vascular, bronchial, gastrointestinal, and genitourinary smooth muscle.

(12 Dec 1998)

receptors, albuminmedical dictionary

Cell surface proteins that bind albumin with high affinity and trigger intracellular changes influencing the behaviour of cells.

(12 Dec 1998)

receptors, aldosteronemedical dictionary

Cytoplasmic proteins that specifically bind aldosterone and mediate its cellular effects. The aldosterone-bound receptor acts in the nucleus to regulate the transcription of specific segments of DNA.

(12 Dec 1998)

receptors, amino acidmedical dictionary

Cell surface proteins that bind amino acids and trigger changes which influence the behaviour of cells. Glutamate receptors are the most common receptors for fast excitatory synaptic transmission in the vertebrate central nervous system, and gaba and glycine receptors are the most common receptors for fast inhibition.

(12 Dec 1998)

receptors, ampamedical dictionary

Cell surface proteins that bind glutamate and directly gate ion channels in cell membranes. Ampa receptors were originally discriminated from other glutamate receptors by their affinity for the agonist ampa (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid). They are probably the most common mediators of fast excitatory synaptic transmission in the central nervous system. Several subtypes have been cloned, and for some types the traditional distinction from kainate receptors may not apply.

(12 Dec 1998)

receptors, androgenmedical dictionary

Proteins, generally found in the cytoplasm, that specifically bind androgens and mediate their cellular actions. The complex of the androgen and receptor migrates to the nucleus where it induces transcription of specific segments of DNA.

(12 Dec 1998)

receptors, angiotensinmedical dictionary

Cell surface proteins that bind angiotensins and trigger intracellular changes influencing the behaviour of cells.

(12 Dec 1998)

receptors, antigenmedical dictionary

Molecules on the surface of b- and T-lymphocytes that recognise and combine with specific antigens.

(12 Dec 1998)

receptors, antigen, B-cellmedical dictionary

Immunoglobulin molecules on the surface of B-lymphocytes that recognise and bind antigen.

(12 Dec 1998)

receptors, antigen, T-cellmedical dictionary

Molecules on the surface of T-lymphocytes that recognise and combine with antigens. The receptors are non-covalently associated with a complex of several polypeptides collectively called CD3 antigens (antigens, CD3). 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.

(12 Dec 1998)

receptors, antigen, T-cell, alpha-betamedical dictionary

T-cell receptors composed of CD3-associated alpha and beta polypeptide chains and expressed primarily in CD4+ or CD8+ T-cells. Unlike immunoglobulins, the alpha-beta T-cell receptors recognise antigens only when presented in association with major histocompatibility (MHC) molecules.

(12 Dec 1998)

receptors, antigen, T-cell, gamma-deltamedical dictionary

T-cell receptors composed of CD3-associated gamma and delta polypeptide chains and expressed primarily in CD4-/CD8- T-cells. The receptors appear to be preferentially located in epithelial sites and probably play a role in the recognition of bacterial antigens. The T-cell receptor gamma/delta chains are separate and not related to the gamma and delta chains which are subunits of CD3 (see antigens, CD3).

(12 Dec 1998)

receptors, aryl hydrocarbonmedical dictionary

Cytoplasmic proteins that bind certain aryl hydrocarbons, translocate to the nucleus, and activate transcription of particular DNA segments. Ah receptors are identified by their high-affinity binding to several carcinogenic or teratogenic environmental chemicals including polycyclic aromatic hydrocarbons found in cigarette smoke and smog, heterocyclic amines found in cooked foods, and halogenated hydrocarbons including dioxins and polychlorinated biphenyls. No endogenous ligand has been identified, but an unknown natural messenger with a role in cell differentiation and development is suspected.

(12 Dec 1998)

receptors, atrial natriuretic factormedical dictionary
receptors, biogenic aminemedical dictionary

Cell surface proteins that bind biogenic amines with high affinity and regulate intracellular signals which influence the behaviour of cells. Biogenic amine is a chemically imprecise term which, by convention, includes the catecholamines epinephrine, norepinephrine, and dopamine, the indoleamine serotonin, the imidazolamine histamine, and compounds closely related to each of these.

(12 Dec 1998)

receptors, bombesinmedical dictionary

Cell surface proteins that bind bombesin or closely related peptides with high affinity and trigger intracellular changes influencing the behaviour of cells. Gastrin- releasing peptide (grp), grp 18-27 (neuromedin c), and neuromedin b are endogenous ligands of bombesin receptors in mammals.

(12 Dec 1998)

receptors, bradykininmedical dictionary

Cell surface receptors that bind bradykinin and related kinins with high affinity and trigger intracellular changes which influence the behaviour of cells. The identified receptor types (b-1 and b-2, or bk-1 and bk-2) recognise the endogenous kallidins, t-kinins, and certain bradykinin fragments as well as bradykinin itself.

(12 Dec 1998)

receptors, calcitoninmedical dictionary

Cell surface proteins that bind calcitonin and trigger intracellular changes which influence the behaviour of cells. Calcitonin receptors outside the nervous system mediate the role of calcitonin in calcium homeostasis. The role of calcitonin receptors in the brain is not well understood.

(12 Dec 1998)

receptors, calcitonin gene-related peptidemedical dictionary

Cell surface proteins that bind calcitonin gene-related peptide (cgrp) with high affinity and trigger intracellular changes which influence the behaviour of cells. Cgrp receptors are present in both the central nervous system and the periphery and are not the same as calcitonin receptors.

(12 Dec 1998)

receptors, calcitriolmedical dictionary

Proteins, usually found in the cytoplasm, that specifically bind calcitriol, migrate to the nucleus, and regulate transcription of specific segments of DNA. Vitamin d is converted in the liver and kidney to calcitriol and ultimately acts through these receptors.

(12 Dec 1998)

receptors, catecholaminemedical dictionary
receptors, ccr5medical dictionary

Seven-transmembrane G-protein-coupled receptors for beta-chemokines. They also function as fusion cofactors for macrophage-tropic HIV-1 strains.

(12 Dec 1998)

receptors, cell surfacemedical dictionary

Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behaviour of the target cell. Cell surface receptors, unlike enzymes, do not chemically alter their ligands.

(12 Dec 1998)

receptors, chemokinemedical dictionary

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.

(12 Dec 1998)

receptors, cholecystokininmedical dictionary

Cell surface proteins that bind cholecystokinin (cck) with high affinity and trigger intracellular changes influencing the behaviour of cells. Cholecystokinin receptors are activated by gastrin as well as by cck-4, cck-8, and cck-33. Activation of these receptors evokes secretion of amylase by pancreatic acinar cells, acid and pepsin by stomach mucosal cells, and contraction of the pylorus and gall bladder. The role of the widespread cck receptors in the central nervous system is not well understood.

(12 Dec 1998)

receptors, cholinergicmedical dictionary

Cell surface proteins that bind acetylcholine with high affinity and trigger intracellular changes influencing the behaviour of cells. Cholinergic receptors are divided into two major classes, muscarinic and nicotinic, based originally on their affinity for nicotine and muscarine. Each group is further subdivided based on pharmacology, location, mode of action, and/or molecular biology.

(12 Dec 1998)

receptors, colony-stimulating factormedical dictionary
receptors, complementmedical dictionary

Molecules on the surface of some B-lymphocytes and macrophages, that recognise and combine with the c3b, c3d, c1q, and c4b components of complement.

(12 Dec 1998)

receptors, complement 3bmedical dictionary

Molecular sites on or in some B-lymphocytes and macrophages that recognise and combine with complement 3b. The primary structure of these receptors reveal that they contain transmembrane and cytoplasmic domains, with their extracellular portion composed entirely of thirty short consensus repeats each having 60 to 70 amino acids.

(12 Dec 1998)

receptors, complement 3dmedical dictionary

Molecular sites on or in B-lymphocytes, follicular dendritic cells, lymphoid cells, and epithelial cells that recognise and combine with complement 3d. Human cr2 serves as a receptor for both c3dg and the gp350/220 glycoprotein of herpes virus 4, human, and binds the monoclonal antibody okb7, which blocks binding of both ligands to the receptor.

(12 Dec 1998)

receptors, concanavalin amedical dictionary

Glycoprotein moieties on the surfaces of cell membranes that bind concanavalin a selectively; the number and location of the sites depends on the type and condition of the cell.

(12 Dec 1998)

receptors, corticotropinmedical dictionary

Cell surface receptors that bind corticotropin (acth, adrenocorticotropic hormone) with high affinity and trigger intracellular changes. Pharmacology suggests there may be multiple acth receptors. An acth receptor has been cloned and belongs to a subfamily of g-protein-coupled receptors. In addition to the adrenal cortex, acth receptors are found in the brain and immune systems.

(12 Dec 1998)

receptors, corticotropin-releasing hormonemedical dictionary

Cell surface proteins that bind corticotropin-releasing hormone with high affinity and trigger intracellular changes which influence the behaviour of cells. The corticotropin releasing-hormone receptors on anterior pituitary cells mediate the stimulation of corticotropin release by hypothalamic corticotropin-releasing factor. The physiological consequence of activating corticotropin-releasing hormone receptors on central neurones is not well understood.

(12 Dec 1998)

receptors, cxcr4medical dictionary

Seven-transmembrane G-protein-coupled receptors for alpha-chemokines. They also function as fusion cofactors for T-cell-tropic HIV-1 strains.

(12 Dec 1998)

receptors, cyclic AMPmedical dictionary

Cell surface proteins that bind cyclic AMP with high affinity and trigger intracellular changes which influence the behaviour of cells. The best characterised cyclic AMP receptors are those of the slime mold dictyostelium discoideum. The transcription regulator cyclic AMP receptor protein of prokaryotes is not included nor are the eukaryotic cytoplasmic cyclic AMP receptor proteins which are the regulatory subunits of cyclic AMP-dependent protein kinases.

(12 Dec 1998)

receptors, cytoadhesinmedical dictionary

A group of integrins that includes the platelet outer membrane glycoprotein gpiib-iiia (platelet glycoprotein gpiib-iiia complex) and the vitronectin receptor (receptors, vitronectin). They play a major role in cell adhesion and serve as receptors for fibronectin, von willebrand factor, and vitronectin.

(12 Dec 1998)

receptors, cytokinemedical dictionary

Cell surface proteins that bind cytokines and trigger intracellular changes influencing the behaviour of cells.

(12 Dec 1998)

receptors, cytoplasmic and nuclearmedical dictionary

Proteins in the cytoplasm or nucleus that specifically bind signalling molecules and trigger changes which influence the behaviour of cells. The major groups are the steroid hormone receptors, which usually are found in the cytoplasm, and the thyroid hormone receptors, which usually are found in the nucleus. Receptors, unlike enzymes, generally do not catalyze chemical changes in their ligands.

(12 Dec 1998)

receptors, dopaminemedical dictionary

Cell-surface proteins that bind dopamine with high affinity and trigger intracellular changes influencing the behaviour of cells.

(12 Dec 1998)

receptors, dopamine d1medical dictionary

A class of dopamine receptors identified by their binding profiles for synthetic ligands, their molecular biology, and, perhaps, by their mode of action.

(12 Dec 1998)

receptors, dopamine d2medical dictionary

A class of dopamine receptors identified by their binding profiles for synthetic ligands, their molecular biology, and, perhaps, their mode of action.

(12 Dec 1998)

receptors, drugmedical dictionary

Proteins that bind specific drugs with high affinity and trigger intracellular changes influencing the behaviour of cells. Drug receptors are generally thought to be receptors for some endogenous substance not otherwise specified.

(12 Dec 1998)

receptors, eicosanoidmedical dictionary

Cell surface proteins that bind eicosanoids with high affinity and trigger intracellular changes influencing the behaviour of cells. Among the eicosanoid receptors are receptors for the prostaglandins, thromboxanes, and leukotrienes.

(12 Dec 1998)

receptors, endothelinmedical dictionary
receptors, epidermal growth factor-urogastronemedical dictionary

Glycoproteins of about 170 kD that have protein kinase activity and span the plasma membranes of growing cells, including tumours. They are activated by the binding of epidermal growth factor-urogastrone which then initiates DNA and protein synthesis. They are not found on mitotically quiescent cells except in the stomach where they control the synthesis and release of digestive enzymes and gastric acid. Transforming growth factor alpha also binds to and activates these receptors.

(12 Dec 1998)

receptors, erythropoietinmedical dictionary

Cell surface proteins that bind erythropoietin with high affinity and trigger intracellular changes influencing the behaviour of cells.

(12 Dec 1998)

receptors, fcmedical dictionary

Molecules found on the surface of some, but not all, B-lymphocytes, T-lymphocytes, and macrophages, which recognise and combine with the fc (crystallizable) portion of immunoglobulin molecules.

(12 Dec 1998)

receptors, fibroblast growth factormedical dictionary

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.

(12 Dec 1998)

receptors, fibronectinmedical dictionary

Specific sites or molecular structures on or in cells with which fibronectins react or to which they bind. Studies have shown that these receptors function in certain types of adhesive contact as well as playing a major role in matrix assembly. These are the traditional fibronectin receptors, also called vla-5 receptors or alpha 5 beta 1 integrins. There are also other integrins that bind fibronectin, including alpha v beta 1.

(12 Dec 1998)

Receptors for activated C Kinasemedical dictionary

Synonym for endosome.

(11 Mar 2008)

receptors, fshmedical dictionary

Cell surface proteins that bind follicle-stimulating hormone (follitropin, fsh) with high affinity and trigger intracellular changes influencing the behaviour of cells.

(12 Dec 1998)

receptors, gabamedical dictionary

Cell-surface proteins that bind gaba with high affinity and trigger changes that influence the behaviour 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.

(12 Dec 1998)

receptors, gaba-amedical dictionary

Cell surface proteins which bind gaba and control an integral membrane chloride channel. Gaba-a receptors are the most prevalent inhibitory neurotransmitter receptors in the brain. Several isoforms have been cloned, and they belong to a superfamily which includes nicotinic receptors, glycine receptors, and 5ht-3 receptors. Most gaba-a receptors have separate modulatory sites sensitive to benzodiazepines and to barbiturates.

(12 Dec 1998)

receptors, gaba-bmedical dictionary

Cell surface proteins which bind gaba and influence cells via interactions with g-proteins. Gaba-b receptors are pharmacologically characterised by their insensitivity to the blocker bicuculline and sensitivity to the agonist l-baclofen. They are found both presynaptically and postsynaptically, and act variously by inhibition of adenylate cyclase, activation of phospholipase a2, activation of potassium channels, and inactivation of voltage-activated calcium channels.

(12 Dec 1998)

receptors, gastrointestinal hormonemedical dictionary
receptors, glucagonmedical dictionary

Cell surface receptors that bind glucagon with high affinity and trigger intracellular changes which influence the behaviour of cells. Activation of glucagon receptors causes a variety of effects; the best understood is the initiation of a complex enzymatic cascade in the liver which ultimately increases the availability of glucose to body organs.

(12 Dec 1998)

receptors, glucocorticoidmedical dictionary

Cytoplasmic proteins that specifically bind glucocorticoids and mediate their cellular effects. The glucocorticoid receptor-glucocorticoid complex acts in the nucleus to induce transcription of DNA. Glucocorticoids were named for their actions on blood glucose concentration, but they have equally important effects on protein and fat metabolism. Cortisol is the most important example.

(12 Dec 1998)

receptors, glutamatemedical dictionary

Cell-surface proteins that bind glutamate and trigger changes which influence the behaviour of cells. Glutamate receptors include ionotropic receptors (ampa, kainate, and n-methyl-d-aspartate receptors), which directly control ion channels, and metabotropic receptors which act through second messenger systems. Glutamate receptors are the most common mediators of fast excitatory synaptic transmission in the central nervous system. They have also been implicated in the mechanisms of memory and of many diseases.

(12 Dec 1998)

receptors, glycinemedical dictionary
receptors, gonadotropinmedical dictionary

Those protein complexes or molecular sites on the surfaces of gonadal and other sensitive cells that bind gonadotropins and thereby modify the functions of those cells; hcg, lh, and fsh are the major specific gonadotropins.

(12 Dec 1998)

receptors, granulocyte-colony-stimulating factormedical dictionary

Receptors that bind and internalise granulocyte-colony-stimulating factor. Their mw is believed to be 150 kD. These receptors are found mainly on a subset of myelomonocytic cells.

(12 Dec 1998)

receptors, granulocyte-macrophage colony-stimulating factormedical dictionary

Receptors that bind and internalise the granulocyte-macrophage stimulating factor. Their mw is believed to be 84 kD. The most mature myelomonocytic cells, specifically human neutrophils, macrophages, and eosinophils, express the highest number of affinity receptors for this growth factor.

(12 Dec 1998)

receptors, growth factormedical dictionary

Cell surface receptors that bind growth or trophic factors with high affinity, triggering intracellular responses which influence the growth, differentiation, or survival of cells.

(12 Dec 1998)

receptors, histaminemedical dictionary

Cell-surface proteins that bind histamine and trigger intracellular changes influencing the behaviour of cells. Histamine receptors are widespread in the central nervous system and in peripheral tissues. Three types have been recognised and designated h1, h2, and h3. They differ in pharmacology, distribution, and mode of action.

(12 Dec 1998)

receptors, histamine h1medical dictionary

A class of histamine receptors discriminated by their pharmacology and mode of action. most histamine h1 receptors operate through the inositol phosphate/diacylglycerol second messenger system. Among the many responses mediated by these receptors are smooth muscle contraction, increased vascular permeability, hormone release, and cerebral glyconeogenesis.

(12 Dec 1998)

receptors, histamine h2medical dictionary

A class of histamine receptors discriminated by their pharmacology and mode of action. Histamine h2 receptors act via g-proteins to stimulate adenylate cylase. Among the many responses mediated by these receptors are gastric acid secretion, smooth muscle relaxation, inotropic and chronotropic effects on heart muscle, and inhibition of lymphocyte function.

(12 Dec 1998)

receptors, histamine h3medical dictionary

A class of histamine receptors discriminated by their pharmacology and mode of action. Histamine h3 receptors were first recognised as inhibitory autoreceptors on histamine-containing nerve terminals and have since been shown to regulate the release of several neurotransmitters in the central and peripheral nervous systems.

(12 Dec 1998)

receptors, HIVmedical dictionary

Cellular receptors that bind the human immunodeficiency virus that causes aids. Included are CD4 antigens, found on t4 lymphocytes, and monocytes/macrophages, which bind to the HIV envelope protein gp120.

(12 Dec 1998)

receptors, IgEmedical dictionary

Specific molecular sites on the surface of b- and T-lymphocytes which combine with iges. Two subclasses exist: low affinity receptors (fc epsilon ri) and high affinity receptors (fc epsilon rii).

(12 Dec 1998)

receptors, IgGmedical dictionary

Specific molecular sites on the surface of various cells, including B-lymphocytes and macrophages, that combine with iggs. Three subclasses exist: fc gamma ri (the CD64 antigen, a low affinity receptor), fc gamma rii (the CD32 antigen, a high affinity receptor), and fc gamma riii (the CD16 antigen, a low affinity receptor).

(12 Dec 1998)

receptors, immunologicmedical dictionary

Cell surface molecules on cells of the immune system that specifically bind surface molecules or messenger molecules and trigger changes in the behaviour of cells. Although these receptors were first identified in the immune system, many have important functions elsewhere.

(12 Dec 1998)

receptors, insulinmedical dictionary

Cell surface proteins that bind insulin and trigger intracellular changes which influence the behaviour of cells. The best understood physiological consequence of insulin receptor activation is increased transport of glucose into most cells, which controls the rate of carbohydrate metabolism. The insulin receptor is a multifunctional protein complex that has intrinsic tyrosine kinase activity and is capable of autophosphorylation.

(12 Dec 1998)

receptors, insulin-like-growth factor Imedical dictionary

Specific proteins on or in cells to which insulin-like growth factor I (somatomedin c) binds and thereby modifies the function of the cells. These receptors contain transmembrane and cytosolic domains, bind igf-I preferentially, and have high-affinity sites for igf-II. The alpha-subunit has a mw of 130 kD and the beta subunit possesses tyrosine kinase activity.

(12 Dec 1998)

receptors, insulin-like-growth-factor IImedical dictionary

Specific proteins on or in cells to which insulin-like growth factor II and mannose-6-phosphate bind and thereby modify the function of the cells. These receptors have a mw of 250 kD and possess no tyrosine kinase activity.

(12 Dec 1998)

receptors, interferonmedical dictionary

Specific molecular sites or structures on or in cells with which interferons react or to which they bind in order to modify the function of the cells. Interferons exert their pleiotropic effects through two different receptors. Alpha- and beta-interferon crossreact with common receptors, while gamma-interferon initiates its biological effects through its own specific receptor system.

(12 Dec 1998)

receptors, interleukinmedical dictionary

Cell surface proteins that bind interleukins and trigger intracellular changes influencing the behaviour of cells.

(12 Dec 1998)

receptors, interleukin-1medical dictionary

Specific molecular sites or structures on cells with which interleukin-1 reacts or to which it binds to modify the function of the cells. The il-1 receptor on T-lymphocytes and fibroblasts is composed of a single polypeptide chain that binds both il-1 alpha and il-1 beta. The molecular weight of this high-affinity receptor is believed to be 80 kD.

(12 Dec 1998)

receptors, interleukin-2medical dictionary

Receptors present on activated t- and B-cells as a complex consisting of a 55 kD peptide, which reacts with the anti-tac monoclonal antibody, and a 75 kD non-tac interleukin-2-binding peptide. The receptor is present in two forms, one with a very high affinity and the other with low affinity for il-2. The high-affinity form appears to mediate exclusively the growth-promoting response to il-2. The receptor is present in large numbers on resting HTLV-I leukaemia cells, but not on normal resting cells.

(12 Dec 1998)

receptors, interleukin-3medical dictionary

Phosphotyrosine-containing proteins, mw 140 kD. They form a stable complex with interleukin-3 with an apparent mass of 170 kD. They are found on a variety of cells and activate interleukin-3.

(12 Dec 1998)

receptors, interleukin-4medical dictionary

Receptors present on a wide variety of haematopoietic and non-haematopoietic cell types and various human tumours. Two forms of the receptor have been described, soluble and membrane-bound. Low affinity and high affinity receptors for il-4 have been reported.

(12 Dec 1998)

receptors, interleukin-6medical dictionary

<chemical>

Receptors present on t cells, mitogen-activated B-cells, peripheral monocytes, and some macrophage- and B-cell-derived tumour cell types. The receptor is a strongly glycosylated protein of 80 kD and a length of 468 amino acids.

Pharmacological action: growth inhibitors.

(12 Dec 1998)

receptors, invertebrate peptidemedical dictionary
receptor sitemedical dictionary

Point of attachment of viruses, hormones, or other activators to cell membranes.

(05 Mar 2000)

receptors, kainic acidmedical dictionary

Cell surface proteins that bind glutamate and directly gate ion channels. Kainic acid receptors were originally discriminated from other glutamate receptors by their affinity for the agonist kainic acid. Activation of kainic acid receptors is generally excitatory to cells. Subtypes have been cloned, and for some the traditional distinction from ampa receptors may not apply.

(12 Dec 1998)

receptors, lamininmedical dictionary

Glycoprotein molecules on the surface of cells that react with or bind to laminin whose function allows the binding of epithelial cells to the basement membrane. The molecular weight of this high-affinity receptor is 67 kD.

(12 Dec 1998)

receptors, ldlmedical dictionary

Receptors on the plasma membrane of nonhepatic cells that specifically bind ldl. The receptors are localised in specialised regions called coated pits. Hypercholesteraemia is caused by an allelic genetic defect of three types: 1) receptors do not bind to ldl; 2) there is reduced binding of ldl; and 3) there is normal binding but no internalization of ldl. In consequence, entry of cholesterol esters into the cell is impaired and the intracellular feedback by cholesterol on 3-hydroxy-3-methylglutaryl CoA reductase is lacking.

(12 Dec 1998)

receptors, leukocyte-adhesionmedical dictionary

Family of proteins associated with the capacity of leukocytes, including lymphocytes, monocytes, and neutrophils, to adhere to each other and to certain substrata, e.g., the c3bi component of complement. Members of this family are the lymphocyte function-associated antigen-1 (lfa-1), the macrophage-1 antigen (mac-1), and the antigen p150,95 or p150,95 leukocyte adhesion protein. They all share a common beta-subunit which is the CD18 antigen. All three of the above antigens are absent in inherited leukocyte-adhesion deficiency syndrome, which is characterised by recurrent bacterial infections, impaired pus formation, and wound healing as well as abnormalities in a wide spectrum of adherence-dependent functions of granulocytes, monocytes, and lymphoid cells.

(12 Dec 1998)

receptors, leukotrienemedical dictionary

Cell-surface receptors that bind leukotrienes with high affinity and trigger intracellular changes influencing the behaviour of cells. The leukotriene receptor subtypes have been tentatively named according to their affinities for the endogenous leukotrienes ltb4, ltc4, ltd4, and lte4.

(12 Dec 1998)

receptors, leukotriene b4medical dictionary

A class of cell surface leukotriene receptors with a preference for leukotriene b4. Leukotriene b4 receptor activation influences chemotaxis, chemokinesis, adherence, enzyme release, oxidative bursts, and degranulation in polymorphonuclear leukocytes. There are at least two subtypes of these receptors. Some actions are mediated through the inositol phosphate and diacylglycerol second messenger systems.

(12 Dec 1998)

receptors, lhmedical dictionary

Those protein complexes or molecular sites on the surfaces and cytoplasm of gonadal cells that bind luteinizing or chorionic gonadotropic hormones and thereby cause the gonadal cells to synthesise and secrete sex steroids. The hormone-receptor complex is internalised from the plasma membrane and initiates steroid synthesis.

(12 Dec 1998)

receptors, lhrhmedical dictionary

Receptors with a 6-kD protein on the surfaces of cells that secrete lh or fsh, usually in the adenohypophysis. Lhrh binds to these receptors, is endocytosed with the receptor and, in the cell, triggers the release of lh or fsh by the cell. These receptors are also found in rat gonads. Inhibin prevents the binding of gnrh to its receptors.

(12 Dec 1998)

receptors, lipoproteinmedical dictionary

Cell surface proteins that bind lipoproteins with high affinity. Lipoprotein receptors in the liver and peripheral tissues mediate the regulation of plasma and cellular cholesterol metabolism and concentration. The receptors generally recognise the apolipoproteins of the lipoprotein complex, and binding is often a trigger for endocytosis.

(12 Dec 1998)

receptors, lymphocyte homingmedical dictionary

Cell surface glycoproteins on lymphocytes and other leukocytes that mediate adhesion to specialised blood vessels called high endothelial venules. Several different classes of lymphocyte homing receptors have been identified, and they appear to target different surface molecules (addressins) on high endothelial venules in different tissues. The adhesion plays a crucial role in the trafficking of lymphocytes.

(12 Dec 1998)

receptors, macrophage colony-stimulating factormedical dictionary

Glycoproteins of mw 165 kD which are encoded by the c-fms proto-oncogene. The binding of csf-1 to its receptors activates an intrinsic tyrosine kinase activity resulting in autophosphorylation of the receptors on tyrosine, rapid receptor down-regulation, and phosphorylation of as yet unidentified physiologic substrates that initiate a mitogenic response.

(12 Dec 1998)

receptors, metabotropic glutamatemedical dictionary

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.

(12 Dec 1998)

receptors, mineralocorticoidmedical dictionary

Cytoplasmic proteins that specifically bind mineralocorticoids and mediate their cellular effects. The receptor with its bound ligand acts in the nucleus to induce transcription of specific segments of DNA. Mineralocorticoids were named for their actions on extracellular electrolyte concentrations. The most important example is aldosterone.

(12 Dec 1998)

receptors, mitogenmedical dictionary

Glycoprotein molecules on the surface of b- and T-lymphocytes, that react with molecules of antilymphocyte sera, lectins, and other agents which induce blast transformation of lymphocytes.

(12 Dec 1998)

receptors, muscarinicmedical dictionary

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 characterised by their cellular actions, pharmacology, and molecular biology.

(12 Dec 1998)

receptors, nerve growth factormedical dictionary

Cell surface receptors that bind nerve growth factor (ngf) and trigger intracellular changes influencing the behaviour of cells. Nerve growth factor receptors mediate the effects of nerve growth factor on the survival and growth of neurones.

(12 Dec 1998)

receptors, neurokinin-1medical dictionary

A class of cell surface receptors for tachykinins with a preference for substance p. Neurokinin-1 (nk-1) receptors have been cloned and are members of the G-protein coupled receptor superfamily. They are found on many cell types including central and peripheral neurones, smooth muscle cells, acinar cells, endothelial cells, fibroblasts, and immune cells.

(12 Dec 1998)

receptors, neurokinin-2medical dictionary

A class of cell surface receptors for tachykinins that prefers neurokinin a (nka, substance k, neurokinin alpha, neuromedin l), neuropeptide k (npk), or neuropeptide gamma over other tachykinins. Neurokinin-2 (nk-2) receptors have been cloned and are similar to other g-protein coupled receptors.

(12 Dec 1998)

receptors, neurokinin-3medical dictionary

A class of cell surface receptors for tachykinins that prefers neurokinin b (neurokinin beta, neuromedin k) over other tachykinins. Neurokinin-3 (nk-3) receptors have been cloned and are members of the g-protein coupled receptor superfamily. They have been found in the central nervous system and in peripheral tissues.

(12 Dec 1998)

receptors, neuropeptidemedical dictionary
receptors, neuropeptide ymedical dictionary
receptors, neurotensinmedical dictionary

Cell surface proteins that bind neurotensin with high affinity and trigger intracellular changes which influence the behaviour of cells. Neurotensin and neurotensin receptors are found in the central nervous system and in the periphery.

(12 Dec 1998)

receptors, neurotransmittermedical dictionary

Cell surface receptors that bind signalling molecules released by neurones and convert these signals into intracellular changes influencing the behaviour of cells. Neurotransmitter is used here in its most general sense, including not only messengers that act to regulate ion channels, but also those which act on second messenger systems and those which may act at a distance from their release sites. Included are receptors for neuromodulators, neuroregulators, neuromediators, and neurohumors, whether or not located at synapses.

(12 Dec 1998)

receptors, nicotinicmedical dictionary

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, molecular biology, and biophysical properties of the channels.

(12 Dec 1998)

receptors, n-methyl-d-aspartatemedical dictionary

A class of ionotropic glutamate receptors characterised 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.

(12 Dec 1998)

receptors, odourantmedical dictionary

Proteins, usually projecting from the cilia of olfactory receptor neurones, that specifically bind odourant molecules and trigger responses in the neurones. The large number of different odourant receptors appears to arise from several gene families or subfamilies rather than from DNA rearrangement.

American spelling: receptors, odorant

(12 Dec 1998)

receptors, oestradiolmedical dictionary

Cytoplasmic proteins that bind oestradiol, migrate to the nucleus, and regulate DNA transcription.

(12 Dec 1998)

receptors, opioidmedical dictionary

Cell membrane proteins that bind opioids and trigger intracellular changes which influence the behaviour of cells. The endogenous ligands for opioid receptors in mammals include three families of peptides, the enkephalins, endorphins, and dynorphins. The receptor classes include mu, delta, and kappa receptors. Sigma receptors bind several psychoactive substances, including certain opioids, but their endogenous ligands are not known.

(12 Dec 1998)

receptors, opioid, deltamedical dictionary

A class of opioid receptors recognised by its pharmacological profile. Delta opioid receptors bind endorphins and enkephalins with approximately equal affinity and have less affinity for dynorphins.

(12 Dec 1998)

receptors, opioid, kappamedical dictionary

A class of opioid receptors recognised by its pharmacological profile. Kappa opioid receptors bind dynorphins with a higher affinity than endorphins which are themselves preferred to enkephalins.

(12 Dec 1998)

receptors, opioid, mumedical dictionary

A class of opioid receptors recognised by its pharmacological profile. Mu opioid receptors bind, in decreasing order of affinity, endorphins, dynorphins, met-enkephalin, and leu-enkephalin. They have also been shown to be molecular receptors for morphine.

(12 Dec 1998)

receptors, oxytocinmedical dictionary

Cell surface proteins that bind oxytocin with high affinity and trigger intracellular changes which influence the behaviour of cells. Oxytocin receptors in the uterus and the mammary glands mediate the hormone's stimulation of contraction and milk ejection. The presence of oxytocin and oxytocin receptors in neurones of the brain probably reflects an additional role as a neurotransmitter.

(12 Dec 1998)

receptors, pancreatic hormonemedical dictionary

Cell surface proteins that bind pancreatic hormones with high affinity and trigger intracellular changes which influence the behaviour of cells. These include receptors for glucagon (secreted by alpha cells), insulin (secreted by beta cells), somatostatin (secreted by delta cells), and pancreatic peptide (secreted by pp cells). Some of these hormones and receptors also support neurotransmission.

(12 Dec 1998)

receptors, parathyroid hormonemedical dictionary
receptors, peptidemedical dictionary

Cell surface receptors that bind peptide messengers with high affinity and regulate intracellular signals which influence the behaviour of cells.

(12 Dec 1998)

receptors, phencyclidinemedical dictionary

Specific sites or molecular structures on cell membranes or in cells with which phencyclidine reacts or to which it binds to elicit the specific response of the cell to phencyclidine. Studies have demonstrated the presence of multiple receptor sites for pcp. These are the pcp/sigma site, which binds both pcp and psychotomimetic opiates but not certain antipsychotics, and the pcp site, which selectively binds pcp analogs.

(12 Dec 1998)

receptors, pituitary hormonemedical dictionary

Cell surface proteins that bind pituitary hormones with high affinity and trigger intracellular changes influencing the behaviour of cells. Since many pituitary hormones are also released by neurones as neurotransmitters, these receptors are also found in the nervous system.

(12 Dec 1998)

receptors, pituitary hormone-regulating hormonemedical dictionary

Cell surface receptors that bind the hypothalamic hormones regulating pituitary cell differentiation, proliferation, and hormone synthesis and release, including the pituitary-releasing and release-inhibiting hormones. The pituitary hormone-regulating hormones are also released by cells other than hypothalamic neurones, and their receptors also occur on non-pituitary cells, especially brain neurones, where their role is less well understood. Receptors for dopamine, which is a prolactin release-inhibiting hormone as well as a common neurotransmitter, are not included here.

(12 Dec 1998)

receptors, platelet-derived growth factormedical dictionary

Specific molecular sites or structures on cell membranes that react with platelet-derived growth factor, its analogs, or antagonists, to elicit or to inhibit the specific response of the cell to this factor. Pdgf binds with different affinities and specificities to two structurally related receptors, the alpha-receptor and the beta-receptor. Both of these receptors are transmembrane proteins with an intracellular, ligand-stimulatable protein kinase domain.

(12 Dec 1998)

receptors, polymeric immunoglobulinmedical dictionary

Specialised fc receptors (receptors, fc) for polymeric immunoglobulins, which mediate transcytosis of polymeric IgA and IgM into external secretions. They are found on the surfaces of epithelial cells and hepatocytes. After binding to IgA, the receptor-ligand complex undergoes endocytosis, transport by vesicle, and secretion into the lumen by exocytosis. Before release, the part of the receptor (secretory component) that is bound to IgA is proteolytically cleaved from its transmembrane tail.

(12 Dec 1998)

receptors, presynapticmedical dictionary
receptors, progesteronemedical dictionary

Specific proteins found in or on cells of progesterone target tissues that specifically combine with progesterone. The cytosol progesterone-receptor complex then associates with the nucleic acids to initiate protein synthesis. There are two kinds of progesterone receptors, a and b. Both are induced by oestrogen and have short half-lives.

(12 Dec 1998)

receptors, prolactinmedical dictionary

Labile proteins on or in prolactin-sensitive cells that bind prolactin initiating the cells' physiological response to that hormone. Mammary casein synthesis is one of the responses. The receptors are also found in placenta, liver, testes, kidneys, ovaries, and other organs and bind and respond to certain other hormones and their analogs and antagonists. This receptor is related to the growth hormone receptor.

(12 Dec 1998)

receptors, prostaglandinmedical dictionary

Cell surface receptors that bind prostaglandins with high affinity and trigger intracellular changes which influence the behaviour of cells. Prostaglandin receptor subtypes have been tentatively named according to their relative affinities for the endogenous prostaglandins. They include those which prefer prostaglandin d2 (dp receptors), prostaglandin e2 (ep1, ep2, and ep3 receptors), prostaglandin f2-alpha (fp receptors), and prostacyclin (ip receptors).

(12 Dec 1998)

receptors, prostaglandin emedical dictionary

Cell surface receptors which bind prostaglandins with a high affinity and trigger intracellular changes which influence the behaviour 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.

(12 Dec 1998)

receptors, purinergicmedical dictionary

Cell surface proteins that bind purines with high affinity and trigger intracellular changes which influence the behaviour of cells. The best characterised classes of purinergic receptors in mammals are the p1 receptors, which prefer adenosine, and the p2 receptors, which prefer ATP or ADP.

(12 Dec 1998)

receptors, purinergic p1medical dictionary

A class of cell surface receptors that prefers adenosine to other endogenous purines. Purinergic p1 receptors are widespread in the body including the cardiovascular, respiratory, immune, and nervous systems. There are at least two pharmacologically distinguishable types (a1 and a2, or ri and ra). The methylxanthines, e.g., caffeine, bind to these receptors, but also have other unrelated effects.

(12 Dec 1998)

receptors, purinergic p2medical dictionary

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. Subtypes have been proposed, usually designated p2 x, y, z, and t. P2x receptors may mediate fast synaptic transmission by ATP. The ADP-preferring p2t receptors in platelets stimulate aggregation.

(12 Dec 1998)

receptors, retinoic acidmedical dictionary

Proteins in the nucleus or cytoplasm that specifically bind retinoic acid or retinol and trigger changes in the behaviour of cells. Retinoic acid receptors, like steroid receptors, are ligand-activated transcription regulators. Several types have been recognised.

(12 Dec 1998)

receptors, sensorymedical dictionary

Specialised neurones or parts of neurones which transduce sensory information and relay it centrally. Included are receptors for stimuli outside the body (exteroceptors) as well as receptors for stimuli from within the body itself (interoceptors and proprioceptors). Sensory receptors may include accessory structures which condition (e.g., filter) the input received by the receptor neurones themselves.

(12 Dec 1998)

receptors, serotoninmedical dictionary

Cell-surface proteins that bind serotonin and trigger intracellular changes which influence the behaviour of cells. Several types of serotonin receptors have been recognised which differ in their pharmacology, molecular biology, and mode of action.

(12 Dec 1998)

receptors, sigmamedical dictionary

A class of cell surface receptors recognised by its pharmacological profile. Sigma receptors were originally considered to be opioid receptors because they bind certain synthetic opioids. However they also interact with a variety of other psychoactive drugs, and their endogenous ligand is not known (although they can react to certain endogenous steroids). Sigma receptors are found in the immune, endocrine, and nervous systems, and in some peripheral tissues.

(12 Dec 1998)

receptors, somatomedinmedical dictionary

Cell surface receptors that bind somatomedins and trigger intracellular changes which influence the behaviour of cells. Studies have disclosed two types of receptors for this family of peptide hormones. The type I receptor is homologous to the insulin receptor and has tyrosine kinase activity. The type II receptor is identical to the mannose-6-phosphate receptor which is important in trafficking of lysosomal enzymes.

(12 Dec 1998)

receptors, somatostatinmedical dictionary

Cell surface proteins that bind somatostatin and trigger intracellular changes which influence the behaviour of cells. Somatostatin is a hypothalamic hormone, a pancreatic hormone, and a central and peripheral neurotransmitter. Activated somatostatin receptors on pituitary cells inhibit the release of growth hormone; those on endocrine and gastrointestinal cells regulate the absorption and utilization of nutrients; and those on neurones mediate somatostatin's role as a neurotransmitter.

(12 Dec 1998)

receptors, somatotropinmedical dictionary

Cell surface proteins that bind somatotropin with high affinity and trigger intracellular changes influencing the behaviour of cells. Activation of growth hormone receptors regulates amino acid transport through cell membranes, RNA translation to protein, DNA transcription, and protein and amino acid catabolism in many cell types. Many of these effects are mediated indirectly through stimulation of the release of somatomedins.

(12 Dec 1998)

receptors, steroidmedical dictionary

Proteins found usually in the cytoplasm or nucleus that specifically bind steroid hormones and trigger changes influencing the behaviour of cells. The steroid receptor-steroid hormone complex regulates the transcription of specific genes.

(12 Dec 1998)

receptors, tachykininmedical dictionary

Cell surface proteins that bind tachykinins with high affinity and trigger intracellular changes influencing the behaviour of cells. Three classes of tachykinin receptors have been characterised, the nk-1, nk-2, and nk-3, which prefer, respectively, substance p, neurokinin a (substance k, neurokinin alpha, neuromedin l), and neurokinin b (neurokinin beta, neuromedin k).

(12 Dec 1998)

receptors, thrombinmedical dictionary

Cell surface proteins that specifically bind thrombin and trigger changes in the behaviour of blood cells. There are at least two types of thrombin receptors on platelets. The higher affinity receptors mediate the inhibition of stimulated adenylate cyclase, the secretion of acid hydrolases, and the activation of phospholipase a2. The lower affinity receptors are linked to phospholipase c and trigger platelet aggregation and exposure of fibrinogen binding sites. A human platelet thrombin receptor has been cloned and is a member of the family of peptide receptors. There are also thrombin receptors on endothelial cells and smooth muscle cells.

(12 Dec 1998)

receptors, thromboxanemedical dictionary
receptors, thyroid hormonemedical dictionary

Proteins, usually found in the nucleus, that specifically bind thyroid hormones and regulate DNA transcription. These proteins, termed c-erba, are activated by hormones and cause differentiation of erythroid progenitor cells which irreversibly lose proliferative potential. Thus c-erba proteins act as growth suppressors. The c-erba proteins are encoded by at least two genes, c-erba alpha and c-erba beta. Each of these has two isoforms. Mutations in the ligand-binding domain of the beta form causes thyroid hormone resistance syndrome.

(12 Dec 1998)

receptors, thyrotropinmedical dictionary

Cell surface proteins that bind thyrotropin and trigger intracellular changes influencing the behaviour of cells. These receptors are present in the nervous system and on cells in the thyroid gland. Autoantibodies to these receptors are implicated in graves', hashimoto's, and other thyroid diseases.

(12 Dec 1998)

receptors, thyrotropin-releasing hormonemedical dictionary

Cell surface receptors that bind thyrotropin releasing hormone (trh) with high affinity and trigger intracellular changes which influence the behaviour of cells. Activated trh receptors in the anterior pituitary stimulate the release of thyrotropin (thyroid-stimulating hormone, tsh). Trh receptors on neurones mediate neurotransmission by trh.

(12 Dec 1998)

receptors, transferrinmedical dictionary

Membrane glycoproteins found in high concentrations on iron-utilizing cells. They specifically bind iron-bearing transferrin, are endocytosed with its ligand and then returned to the cell surface where transferrin without its iron is released.

(12 Dec 1998)

receptors, transforming growth factor betamedical dictionary
receptors, tumour necrosis factormedical dictionary

Cell surface receptors that bind tumour necrosis factor and trigger changes which influence the behaviour of cells. The two recognised tumour necrosis factor receptors are designated alpha and beta receptors. Both receptors bind both alpha and beta tumour necrosis factors with high affinity, and both are members of the nerve growth factor receptor family.

American spelling: receptors, tumor necrosis factor

(12 Dec 1998)

receptors, vasoactive intestinal peptidemedical dictionary
receptors, vasopressinmedical dictionary

Specific molecular sites or structures on or in cells that vasopressins react or to which they bind in order to modify the function of the cells. Two types of vasopressin receptor exist, the v1 receptor and the v2 receptor. The v1 receptor can be subdivided into v1a and v1b (formerly v3) receptors.

(12 Dec 1998)

receptors, very late antigenmedical dictionary

Members of the integrin family appearing late after T-cell activation. They are a family of proteins initially identified at the surface of stimulated T-cells, but now identified on a variety of cell types. At least six vla antigens have been identified as heterodimeric adhesion receptors consisting of a single common beta-subunit and different alpha-subunits.

(12 Dec 1998)

receptors, virusmedical dictionary

<virus>

<virology> Specific molecular components of the cell capable of recognizing and interacting with a virus, and which, after binding it, are capable of generating some signal that initiates the chain of events leading to the biological response.

(12 Dec 1998)

receptors, vitronectinmedical dictionary

Alpha-v beta-3 integrins that bind vitronectin with high affinity and play a role in cell migration. They also bind fibrinogen, von willebrand factor, osteopontin, and thrombospondin. The highly homologous alpha-v beta-5 integrin also binds vitronectin, but mediates simple adhesion.

(12 Dec 1998)