| receptors, insulin-like-growth factor I | Specific proteins on or in cells to which insulin-like growth factor I (somatomedin c) binds and thereby modifies the function of the cells. These receptors contain transmembrane and cytosolic domains, bind igf-I preferentially, and have high-affinity sites for igf-II. The alpha-subunit has a mw of 130 kD and the beta subunit possesses tyrosine kinase activity. (12 Dec 1998) |
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| receptors, insulin-like-growth-factor II | Specific proteins on or in cells to which insulin-like growth factor II and mannose-6-phosphate bind and thereby modify the function of the cells. These receptors have a mw of 250 kD and possess no tyrosine kinase activity. (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, nerve growth factor | Cell surface receptors that bind nerve growth factor (ngf) and trigger intracellular changes influencing the behaviour of cells. Nerve growth factor receptors mediate the effects of nerve growth factor on the survival and growth of neurons. (12 Dec 1998) |
| receptors, platelet-derived growth factor | Specific molecular sites or structures on cell membranes that react with platelet-derived growth factor, its analogs, or antagonists, to elicit or to inhibit the specific response of the cell to this factor. Pdgf binds with different affinities and specificities to two structurally related receptors, the alpha-receptor and the beta-receptor. Both of these receptors are transmembrane proteins with an intracellular, ligand-stimulatable protein kinase domain. (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) |
| G factor | The single common variance or factor that is common to (i.e., empirically intercorrelates with) different intelligence tests (general). A substance required for the growth of a specific organism. (05 Mar 2000) |
| Castle's intrinsic factor | A mucoprotein normally secreted by the epithelium of the stomach and that binds vitamin B12, the intrinsic factor/B12 complex is selectively absorbed by the distal ileum, though only the vitamin is taken into the cell. (18 Nov 1997) |
| maturation factor | <biochemistry> Member of the water soluble B vitamin group, important in the proper function of the nervous system and important in proper carbohydrate, protein and fat metabolism. (27 Sep 1997) |
| maturation-promoting factor | <enzyme> A protein kinase that drives both the mitotic and meiotic cycles in all eukaryotic organisms. In meiosis it induces immature oocytes to undergo meiotic maturation. In mitosis it has a role in the G2/M phase transition. Once activated by cyclins, maturation-promoting factor directly phosphorylates some of the proteins involved in nuclear envelope breakdown, chromosome condensation, spindle assembly, and the degradation of cyclins. The catalytic subunit of maturation-promoting factor is protein p34cdc2. Acronym: MPF (12 Dec 1998) |
| reflection factor | <microscopy> The ratio of reflected light from a surface to the incident light. This is sometimes called the coefficient of reflection. Unless especially stated it takes into account both specular and diffuse reflection. (05 Aug 1998) |
| cattell personality factor questionnaire | Self report questionnaire which yields 16 scores on personality traits, such as reserved vs. Outgoing, humble vs. Assertive, etc. (12 Dec 1998) |
| glass factor | <chemical> Stable blood coagulation factor activated by contact with the subendothelial surface of an injured vessel. Along with prekallikrein, it serves as the contact factor that initiates the intrinsic pathway of blood coagulation. Kallikrein activates factor xii to xiia. Deficiency of factor xii, also called the hageman trait, leads to increased incidence of thromboembolic disease. Chemical name: Blood-coagulation factor XII (12 Dec 1998) |
| relaxation factor | Substance presumably involved in the return of muscle fibrils to the resting state after nervous stimulation ceases, postulated to act by withdrawing Calcium from myosin-ATPase sites. (05 Mar 2000) |