| receptors, laminin | 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) |
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| receptors, ldl | 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-adhesion | 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, leukotriene | 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 b4 | 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, lh | 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, lhrh | 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, lipoprotein | 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 homing | 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 factor | 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 glutamate | 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, mineralocorticoid | 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, mitogen | 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, muscarinic | 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, n-methyl-d-aspartate | 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) |