| receptors, antigen, B-cell | Immunoglobulin molecules on the surface of B-lymphocytes that recognise and bind antigen. (12 Dec 1998) |
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| receptors, antigen, T-cell | 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-beta | 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-delta | 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 hydrocarbon | 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 factor | Cell surface proteins that bind atrial natriuretic factor with high affinity and trigger intracellular changes influencing the behaviour of cells. (12 Dec 1998) |
| receptors, biogenic amine | 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, bombesin | 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, bradykinin | 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, calcitonin | 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 peptide | 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, calcitriol | 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, catecholamine | Cell surface proteins that bind catecholamines with high affinity and trigger intracellular changes which influence the behaviour of cells. The catecholamine messengers epinephrine, norepinephrine, and dopamine are synthesised from tyrosine by a common biosynthetic pathway. (12 Dec 1998) |
| receptors, ccr5 | 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 surface | 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) |