| receptors, histamine | 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) |
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| receptors, histamine h1 | 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 h2 | 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 h3 | 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, HIV | 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, IgE | 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, IgG | 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, immunologic | 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, insulin | 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, interferon | 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, interleukin | Cell surface proteins that bind interleukins and trigger intracellular changes influencing the behaviour of cells. (12 Dec 1998) |
| receptors, interleukin-1 | 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-2 | 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-3 | 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-4 | 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) |