INTERACTION OF INVERTEBRATE MYOSINS WITH ACTIN

为了研究无脊椎动物肌肉的调节，我们分离了两种肌球蛋白 从马蹄蟹的横纹肌和从 水虫Lethocerus的飞行肌肉，并检查了滑动 肌动蛋白细丝在纯化的肌球蛋白上的速度。鲜为人知 关于莱瑟龙飞行肌肉的调节。我们的初步结果 说明粗丝(磷酸化)调控系统可能发挥作用 在雷瑟龙的飞行肌肉中扮演着重要的角色。蛙纹肌是 已知受Thin(肌钙蛋白和原肌球蛋白)和 粗(磷酸化)纤维调节系统，是钙- 依附的。我们的实验证明，这两种状态中的任何一种 系统是主导的，并发生肌动蛋白细丝的运动，两者 肌球蛋白磷酸化与肌钙蛋白和原肌球蛋白活化 系统是必需的。来自不同来源的原肌球蛋白似乎 当与肌动蛋白结合时，将滑动速度提高5-10倍。钙有作用 在肌钙蛋白和肌钙蛋白都不存在的情况下，不会显著改变速度 原肌球蛋白。蛙类胰酶磷酸肽的部分序列分析 肌球蛋白轻链在肌球蛋白光作用下的磷酸化 21 kD的链激酶产量ATS(PO4)NVFAMFEQNQIA，以及 31kD轻链的SGS(PO4)NVFSMFTE。序列的比较 提示该基因的磷酸化位点附近的序列 轻链与脊椎动物的肌球蛋白更相似 轻链比脊椎动物的横纹肌肌球蛋白轻链。

To study the regulation of invertebrate muscle, we isolated myosin both from the striated muscle of Limulus - the horseshoe crab and from the flight muscle of Lethocerus - a water bug, and examined the sliding velocity of actin filaments over the purified myosins. Little is known about the regulation of Lethocerus flight muscle. Our preliminary results show that the thick (phosphorylation) filament regulatory system may play an important role in Lethocerus flight muscle. Limulus striated muscle is known to be regulated by both the thin (troponin and tropomyosin) and thick (phosphorylation) filament regulatory systems which are calcium- dependent. Our experiments demonstrated that the "off" state of either system is dominant and for the movement of actin filaments to occur, both phosphorylated Limulus myosin and an activated troponin and tropomyosin system are required. Tropomyosin from different sources appeared to increase the sliding velocity 5-10 fold when bound to actin. Calcium does not alter the velocity significantly in the absence of both troponin and tropomyosin. Partial sequences of the tryptic phosphopeptides of Limulus myosin light chains following the phosphorylation by gizzard myosin light chain kinase yield ATS(PO4)NVFAMFEQNQIA for the 21 kD, and SGS(PO4)NVFSMFTE for the 31 kD light chain. Comparison of sequences suggests that the sequence around the phosphorylation site of Limulus light chains is more similar to that of vertebrate smooth muscle myosin light chain than to that of vertebrate striated muscle myosin light chain.