Marston S B, Lehman W
Biochem J. 1985 Nov 1;231(3):517-22. doi: 10.1042/bj2310517.
Thin-filament preparations from four smooth muscle types (gizzard, stomach, trachea, aorta) all activate myosin MgATPase activity, are regulated by Ca2+, and contain actin, tropomyosin and a 120000-140000-Mr protein in the molar proportions 1:1/7:1/26. The 120000-140000-Mr protein from all sources is a potent inhibitor of actomyosin ATPase activity. Peptide-mapping and immunological evidence is presented showing that it is identical with caldesmon. Quantitative immunological data suggest that caldesmon is a component of all the thin filaments and that the thin-filament-bound caldesmon accounts for all the caldesmon in intact tissue. The myosin light-chain kinase content of thin-filament preparations was found to be negligible. We propose that caldesmon-based thin-filament Ca2+ regulation is a physiological mechanism in all smooth muscles.
来自四种平滑肌类型（砂囊、胃、气管、主动脉）的细肌丝制剂均能激活肌球蛋白MgATP酶活性，受Ca2+调节，且含有肌动蛋白、原肌球蛋白和一种分子量为120000 - 140000的蛋白质，其摩尔比例为1:1/7:1/26。来自所有来源的分子量为120000 - 140000的蛋白质是肌动球蛋白ATP酶活性的强效抑制剂。本文提供了肽图谱和免疫学证据，表明它与钙调蛋白相同。定量免疫学数据表明，钙调蛋白是所有细肌丝的一个组成部分，且结合在细肌丝上的钙调蛋白占完整组织中所有钙调蛋白的全部。发现细肌丝制剂中的肌球蛋白轻链激酶含量可忽略不计。我们提出，基于钙调蛋白的细肌丝Ca2+调节是所有平滑肌中的一种生理机制。
