Lal A A, Korn E D
Biochemistry. 1986 Mar 11;25(5):1154-8. doi: 10.1021/bi00353a031.
At saturating concentrations, tropomyosin inhibited the rate of spontaneous polymerization of ATP-actin and also inhibited by 40% the rates of association and dissociation of actin monomers to and from filaments. However, tropomyosin had no effect on the critical concentrations of ATP-actin or ADP-actin. The tropomyosin-troponin complex, with or without Ca2+, had a similar effect as tropomyosin alone on the rate of polymerization of ATP-actin. Although tropomyosin binds to F-actin and not to G-actin, the absence of an effect on the actin critical concentration is probably explicable in terms of the highly cooperative nature of the binding of tropomyosin to F-actin and its very low affinity for a single F-actin subunit relative to the affinity of one actin subunit for another in F-actin.
在饱和浓度下，原肌球蛋白抑制了ATP - 肌动蛋白的自发聚合速率，并且还将肌动蛋白单体与细丝结合和解离的速率分别抑制了40%。然而，原肌球蛋白对ATP - 肌动蛋白或ADP - 肌动蛋白的临界浓度没有影响。无论有无Ca2+，原肌球蛋白 - 肌钙蛋白复合物对ATP - 肌动蛋白聚合速率的影响与单独的原肌球蛋白相似。尽管原肌球蛋白与F - 肌动蛋白结合而不与G - 肌动蛋白结合，但对肌动蛋白临界浓度没有影响可能可以用原肌球蛋白与F - 肌动蛋白结合的高度协同性质以及它对单个F - 肌动蛋白亚基的亲和力相对于F - 肌动蛋白中一个肌动蛋白亚基对另一个的亲和力非常低来解释。
