Reversible loss of calcium control of tension in scallop striated muscle associated with the removal of regulatory light chains
Reversible loss of calcium control of tension in scallop striated muscle associated with the removal of regulatory light chains
复制标题
与调节性轻链去除相关的扇贝横纹肌张力钙控制的可逆性丧失
作者：
R. Simmons;A. Szent
钙对软体动物肌肉肌球蛋白、肌动球蛋白和肌原纤维ATP酶活性的控制需要肌球蛋白的一种特殊的“调节”轻链的存在1，2。在这些肌肉肌钙蛋白是没有发现在化学计量的量，并不作为一个主要的监管component2，3。在扇贝肌肉中，每个肌球蛋白的两条调节轻链之一通过用EDTA 2，4降低二价阳离子浓度而容易且可逆地去除，结果制剂对钙变得“脱敏”，即，无论是否存在钙，ATP酶活性都是最大的。“再致敏”可以通过调节轻链与肌球蛋白或肌原纤维的重组来实现。我们已经将这些研究扩展到扇贝肌肉制备（化学“剥皮”纤维束），其中收缩机械是完整的，我们在这里表明，调节轻链可以被删除和重组，伴随着损失和恢复的钙控制张力生产。
THE control by calcium of the ATPase activities of myosin, actomyosin and myofibrils from molluscan muscles requires the presence of a particular ‘regulatory’ light chain of myosin1,2. In these muscles troponin is not found in stoichiometric amounts and does not function as a major regulatory component2,3. In scallop muscles one of the two regulatory light chains per myosin is readily and reversibly removed by reducing the divalent cation concentration with EDTA2,4, with the result that the preparations become ‘desensitised’ to calcium, that is, the ATPase activity is maximal whether or not calcium is present. ‘Resensitising’ can be achieved by the recombination of regulatory light chains with myosin or myofibrils. We have extended these studies to a scallop muscle preparation (chemically ‘skinned’ fibre bundles) in which the contractile machinery is intact, and we show here that the regulatory light chains can be removed and recombined, with a concomitant loss and recovery of calcium control over tension production.