Ebashi S
J Mol Cell Cardiol. 1984 Feb;16(2):129-36. doi: 10.1016/s0022-2828(84)80701-4.
Troponin regulation can be divided into two categories, primary and secondary. While the former underlies the processes common to troponin-regulated muscles, the latter varies between different types of muscle. One example of secondary regulation is the Ca2+ dependent interaction of troponin T and troponin C, which tends to suppress the myosin-actin-ATP interaction at relatively high Ca2+ concentrations, say, 10(-4)M. This interaction is marked in fast skeletal muscle, but weak in cardiac muscle. Since the Ca2+ concentration in fast skeletal muscle can physiologically reach a high level, this interaction may be considered as a kind of self-defense mechanism to avoid excess contraction. Cardiac muscle, which carries out its contractile cycle at lower Ca2+ concentrations, does not require such a mechanism, but under pathological conditions where the Ca2+ concentration could reach a high level, the lack of this mechanism might be detrimental to the contractile system.
肌钙蛋白调节可分为两类，即初级调节和次级调节。前者是肌钙蛋白调节的肌肉所共有的过程的基础，而后者在不同类型的肌肉之间存在差异。次级调节的一个例子是肌钙蛋白T和肌钙蛋白C之间的Ca2+依赖性相互作用，在相对较高的Ca2+浓度（如10^(-4)M）下，这种相互作用倾向于抑制肌球蛋白-肌动蛋白-ATP相互作用。这种相互作用在快肌中明显，但在心肌中较弱。由于快肌中的Ca2+浓度在生理上可达到较高水平，这种相互作用可被视为一种避免过度收缩的自我防御机制。心肌在较低的Ca2+浓度下进行其收缩周期，不需要这种机制，但在Ca2+浓度可能达到高水平的病理条件下，缺乏这种机制可能对收缩系统有害。
