- In cell biology, a structure on the surface of a cell (or inside a cell) that selectively receives and binds a specific substance. There are hoards of receptors. There are receptors for insulin, receptors for low-density lipoproteins
- In cell biology, a structure on the surface of a cell (or inside a cell) that selectively receives and binds a specific substance. There are hoards of receptors. There are receptors for insulin, receptors for low-density lipoproteins (LDL), etc. To take an example, the receptor for substance P, a molecule that acts as a messenger for the sensation of pain, is a unique harbor on the cell surface where substance P docks. Without this receptor, substance P cannot dock and cannot deliver its message of pain. Variant forms of nuclear hormone receptors mediate processes such as cholesterol metabolism and fatty acid production. Some hormone receptors are implicated in diseases such as diabetes and certain types of cancer. A receptor called PXR appears to jump-start the body's response to unfamiliar chemicals and may be involved in drug-drug interactions. In neurology, however, a receptor may have quite a different meaning. It may refer to the terminal of a sensory nerve that receives and responds to stimuli.
* * *1. A structural protein molecule on the cell surface or within the cytoplasm that binds to a specific factor, such as a drug, hormone, antigen, or neurotransmitter. 2. C. Sherrington term for any one of the various sensory nerve endings in the skin, deep tissues, viscera, and special sense organs. [L. receiver, fr. recipio, to receive]- adrenergic receptors reactive components of effector tissues, most of which are innervated by adrenergic postganglionic fibers of the sympathetic nervous system. Such receptors can be activated by norepinephrine and/or epinephrine and by various adrenergic drugs; r. activation results in a change in effector tissue function, such as contraction of arteriolar muscles or relaxation of bronchial muscles; adrenergic receptors are divided into α-receptors and β-receptors, on the basis of their response to various adrenergic activating and blocking agents. SYN: adrenoceptor, adrenoreceptors.- α-adrenergic receptors adrenergic receptors in effector tissues capable of selective activation and blockade by drugs; conceptually derived from the ability of certain agents, such as phenoxybenzamine, to block only some adrenergic receptors and of other agents, such as methoxamine, to activate only the same adrenergic receptors. Such receptors are designated as α-receptors. Their activation results in physiologic responses such as increased peripheral vascular resistance, mydriasis, and contraction of pilomotor muscles.- β-adrenergic receptors adrenergic receptors in effector tissues capable of selective activation and blockade by drugs; conceptually derived from the ability of certain agents, such as propranolol, to block only some adrenergic receptors and of other agents, such as isoproterenol, to activate only the same adrenergic receptors. Such receptors are designated as β-receptors. Their activation results in physiologic responses such as increases in cardiac rate and force of contraction (β1), and relaxation of bronchial and vascular smooth muscle (β2) contained in skeletal muscle.- AMPA r. a type of glutamate r. that participates in excitatory neurotransmission and also binds α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid and acts as a cation channel. SYN: quisqualate r..- angiotensin r. cell-surface G-protein–coupled receptors that mediate the effects of angiotensin II. Two types are recognized: AT1 and AT2; the former mediates the powerful vascular smooth-muscle contraction responsible for the hypertensive response produced by angiotensin II; the latter is not sufficiently understood to be assigned any physiologic function.- ANP receptors cell s