Fourteen actin-binding sites on tropomyosin?

摘要: TROPOMYOSIN plays an important part in the control of muscle contraction. It is a rod-shaped, coiled-coil molecule, about 410 A long, composed two parallel α-helical chains which are register1–4. lies grooves actin double helix all known types filament and normally thought to be associated with seven units5–7. Calcium regulates contraction vertebrate skeletal by its influence on troponin, turn leads movement tropomyosin groove8–10, thereby exposing (in ‘on’ position) or masking ‘off’ myosin cross-bridge binding areas. The position troponin-binding site fairly precisely (ref. 11 review ref. 4), but actin-binding sites have not yet been identified. Here, we analyse fourteen-fold periodicity amino acid sequence α-tropomyosin12 from rabbit propose that it pairs quasi-equivalent sites. Parry13 Stone et al.12 first noted several series repeat 19½ residues, areas low acidic residues spaced 40 apart. There also slightly irregular 42-residue resulting gene duplication14 phase them. We used Fourier analysis make objective systematic search for periodicities distributions acidic, basic nonpolar groups, here assess their significance.