| receptors, thyrotropin | 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) |
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| receptors, thyrotropin-releasing hormone | 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 neurons mediate neurotransmission by trh. (12 Dec 1998) |
| receptors, transferrin | 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 beta | Cell-surface proteins that bind transforming growth factor beta and trigger changes influencing the behaviour of cells. Two types of transforming growth factor receptors have been recognised. They differ in affinity for different members of the transforming growth factor beta family and in cellular mechanisms of action. Transforming growth factor alpha binds to the same receptors as epidermal growth factor (see receptors, epidermal growth factor-urogastrone). (12 Dec 1998) |
| receptors, tumour necrosis factor | 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. (12 Dec 1998) |
| receptors, vasoactive intestinal peptide | Cell surface proteins that bind vasoactive intestinal peptide (vip) with high affinity and trigger intracellular changes which influence the behaviour of cells. (12 Dec 1998) |
| receptors, vasopressin | 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 antigen | 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, virus | 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, vitronectin | 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) |
| cholinergic receptors | Chemical sites in effector cells or at synapses through which acetylcholine exerts its action. (05 Mar 2000) |
| muscarinic receptors | Membrane-bound proteins whose extracellular domain contains a recognition site for acetylcholine (ACh); combination of Ach with the receptor initiates a physiologic change (slowing of heart rate, increased glandular secretory activity and stimulation of smooth muscle contractions); changes are observed after treatment with the mushroom alkaloid, muscarine. Muscarinic receptors are to be distinguished from nicotinic receptors. (05 Mar 2000) |
| saturation of receptors | Saturation, the state in which all receptors are effectively occupied all the time, can be said to occur in a simple binding equilibrium when the concentration of ligand is more than 5 times the Kd value, although strictly this will only be true at infinite ligand concentration. (18 Nov 1997) |
| pulmonary stretch receptors | Stretch receptors found in the bronchi and bronchioles. Pulmonary stretch receptors are sensors for a reflex which stops inspiration. In humans, the reflex is protective and is probably not activated during normal respiration. (12 Dec 1998) |
| sensory receptors | Peripheral endings of afferent neurons. (05 Mar 2000) |