Ebashi S, Nonomura Y, Nakamura S, Nakasone H, Kohama K
Fed Proc. 1982 Oct;41(12):2863-7.
Our view about the Ca regulation of smooth muscle contraction can be summarized as follows: the regulatory system is actin-linked and consists of tropomyosin and leiotonin; the latter is a complex of two proteins, leiotonin A, the regulatory moiety, and leiotonin C, the Ca-binding moiety. Leiotonin resembles troponin in some respects, but is clearly different in that it has no affinity for tropomyosin and is effective at a leiotonin/actin molar ratio of less than 1:50. The methods of preparing leiotonin were critically reviewed and a suggestion was provided for the development of a new procedure. References were also made to our idea that the myosin light chain phosphorylation may not play an essential role in smooth muscle contraction. With reference to a new type of actin-linked factor from Physarum polycephalum through which Ca2+ represses the actin-myosin-ATP interaction, the diversity of the modes of action of Ca2+ was discussed.
调节系统与肌动蛋白相连，由原肌球蛋白和亮抑素组成；后者是两种蛋白质的复合物，即亮抑素A（调节部分）和亮抑素C（钙离子结合部分）。亮抑素在某些方面类似于肌钙蛋白，但明显不同的是它对原肌球蛋白没有亲和力，并且在亮抑素/肌动蛋白摩尔比小于1:50时有效。对制备亮抑素的方法进行了严格审查，并为开发新方法提供了建议。还提及了我们的观点，即肌球蛋白轻链磷酸化可能在平滑肌收缩中不发挥重要作用。参照多头绒泡菌中一种新型的与肌动蛋白相连的因子，通过该因子钙离子可抑制肌动蛋白-肌球蛋白-ATP相互作用，讨论了钙离子作用模式的多样性。
