Regulation of actomyosin interactions in Limulus muscle proteins.
Regulation of actomyosin interactions in Limulus muscle proteins.
复制标题
鲎肌肉蛋白中肌动球蛋白相互作用的调节。
DOI：
10.1016/s0021-9258(18)53761-3
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
J. Sellers
中科院分区：
文献类型：
--
作者：
F. Wang;B. Martin;J. Sellers
鲎横纹肌的收缩受钙离子与肌钙蛋白-原肌球蛋白依赖性细丝阵列的结合和肌球蛋白轻链激酶依赖性肌球蛋白磷酸化的调节。我们已经从鲎横纹肌分离出肌球蛋白，并研究了这两个调节系统如何影响肌动蛋白丝在肌球蛋白上的滑动速度，使用体外运动试验。我们的研究结果表明，在ATP的存在下，鲎肌球蛋白必须磷酸化，以移动肌动蛋白丝。肌动蛋白丝与去磷酸化的鲎肌球蛋白相互作用时没有观察到运动。肌动蛋白运动不需要钙。相反，当肌钙蛋白和原肌球蛋白都与肌动蛋白丝结合时，肌动蛋白丝在磷酸化肌球蛋白上的运动需要钙。这些结果表明，无论是薄丝或厚丝调节系统的“关闭”状态是占主导地位的，并为运动的发生，磷酸化的鲎肌球蛋白和激活的肌钙蛋白原肌球蛋白系统是必需的。原肌球蛋白本身增加肌动蛋白丝的滑动速度超过磷酸化的鲎肌球蛋白约10倍，在钙离子非依赖性的方式。来自火鸡肌胃平滑肌、牛心肌和鲎肌的原肌球蛋白在增加速度方面都有深远的影响。单独的肌钙蛋白不会改变速度。在通过肌球蛋白轻链激酶磷酸化后产生的鲎肌球蛋白调节轻链的胰蛋白酶磷酸肽的部分序列产生21 kDa的ATS（PO 4）NVFAMFEQNQIA和31-kDa的SGS（PO 4）NVFSMFT轻链。
Contraction of striated muscle from Limulus polyphemus, the horseshoe crab, is regulated by both calcium binding to a troponin-tropomyosin-dependent thin filament array and a myosin light chain kinase-dependent phosphorylation of myosin. We have isolated myosin from Limulus striated muscle and examined how these two regulatory systems affect the sliding velocity of actin filaments over myosin, using an in vitro motility assay. Our results show that in the presence of ATP, Limulus myosin must be phosphorylated in order to move actin filaments. No movement was observed for actin filaments interacting with dephosphorylated Limulus myosin. Calcium was not required for actin movement. In contrast, when both troponin and tropomyosin are bound to actin filaments, calcium is required for the movement of actin filaments over phosphorylated myosin. These results demonstrate that the “off” state of either the thin filament or thick filament regulatory system is dominant and that for the movement to occur, both phosphorylated Limulus myosin and an activated troponin-tropomyosin system are required. Tropomyosin by itself increases the sliding velocity of actin filaments over phosphorylated Limulus myosin about 10-fold in a calcium-independent manner. Tropomyosins from turkey gizzard smooth muscle, bovine cardiac muscle, and Limulus muscle all have a profound effect in increasing the velocity. Troponin alone does not change the velocity. Partial sequences of the tryptic phosphopeptides of Limulus myosin regulatory light chains generated following the phosphorylation by gizzard myosin light chain kinase yield ATS(PO4)NVFAMFEQNQIA for 21 kDa and SGS(PO4)NVFSMFT for 31-kDa light chain.