| tropinone reductase | <enzyme> A stereospecific reductase; reduces tropinone to pseudotropine (tropan-3beta-ol); belongs to the NADPH-dependent, class b oxidoreductases; see also the stereospecifically opposite tropinone reductase I (tropine-forming reductase) Registry number: EC 1.1.1.236 Synonym: tropinone reductase II, pseudotropine-forming reductase (26 Jun 1999) |
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| tropism | <biology> The movement of an organism in response to an external source of stimulus, usually toward or away from it. Examples of stimuli are light, heat, food, or chemicals. (09 Oct 1997) |
| tropocollagen | <protein> Subunit from which collagen fibrils self assemble: generated from procollagen by proteolytic cleavage of the extension peptides. (18 Nov 1997) |
| tropoelastin | A salt-soluble precursor of elastin. Lysyl oxidase is instrumental in converting it to elastin in connective tissue. (12 Dec 1998) |
| tropological | Characterised by tropes; varied by tropes; tropical. Tropolog"ically. Origin: Gr., cf. F. Tropologique. See Tropology. Source: Websters Dictionary (01 Mar 1998) |
| tropology | <study> A rhetorical mode of speech, including tropes, or changes from the original import of the word. Origin: Gr.; a trope + discourse: cf. F. Tropologie. Source: Websters Dictionary (01 Mar 1998) |
| tropolone | <chemical> 2-hydroxy-2,4,6-cycloheptatrien-1-one. Chemical name: 2,4,6-Cycloheptatrien-1-one, 2-hydroxy- (12 Dec 1998) |
| tropometer | Any instrument for measuring the degree of rotation or torsion, as of the eyeball or the shaft of a long bone. Origin: G. Trope, a turning, + metron, measure (05 Mar 2000) |
| tropomodulin | <protein> Tropomyosin binding protein that weakens tropomyosin actin interaction. Found in erythrocyte membrane skeleton and in various nonerythroid cells. Kreis & Vale 1993 (18 Nov 1997) |
| tropomyosin | <protein> Protein (66 kD) associated with actin filaments both in cytoplasm and (in association with troponin) in the thin filament of striated muscle. Composed of two elongated _ helical chains (each about 33 kD), 40 nm long, 2 nm diameter. Each chain has six or seven similar domains and interacts with as many G actin molecules as there are domains. Not only does the binding of tropomyosin stabilise the F actin, but the association with troponin in striated muscle is important in control by calcium ions. (18 Nov 1997) |
| tropomyosin kinase | <enzyme> From chick embryo; requires mg; ca and cyclic AMP not needed Registry number: EC 2.7.1.132 (26 Jun 1999) |
| troponin | <protein> Complex of three proteins, Troponins C, I, & T, associated with tropomyosin and actin on the thin filament of striated muscle, upon which it confers calcium sensitivity. There is one troponin complex per tropomyosin. Troponin C (18 kD) binds calcium ions reversibly, has a variable number of EF hand motifs and is the least variable of the subunits. TnC binds TnI & TnT, but not actin. Troponin I (23 kD) binds to actin and at 1:1 stoichiometry can inhibit the actin myosin interaction on its own. Troponin T (37 kD) binds strongly to tropomyosin. (18 Nov 1997) |
| troponin c | One of the three polypeptide chains that make up the troponin complex. It is a calcium-binding protein. (12 Dec 1998) |
| troponin I | One of the three polypeptide chains that make up the troponin complex. It is an inhibitory protein that binds to actin. (12 Dec 1998) |
| troponin phosphatase | <enzyme> Dephosphorylates serine 20-phosphate of the inhibitor subunit tn-1, of cardiac troponin Registry number: EC 3.1.3.- (26 Jun 1999) |