Levitskiĭ D I, Shuvalova L A, Kalmykov P V, Poglazov B F
Biokhimiia. 1987 May;52(5):813-24.
The effect of phosphorylation of light chains-2 (LC2) of rabbit skeletal muscle myosin on the interaction of myosin minifilaments with F-actin as well as on the actin-stimulated Mg2+-ATPase of minifilaments was studied. It was shown that in the absence of KCl the degree of F-actin-induced stimulation of myosin minifilament Mg2+-ATPase with phosphorylated LC2 exceeds 2-4-fold that with unphosphorylated LC2. Phosphorylation of LC2 considerably increases the rate of actin-stimulated Mg2+-ATPase reaction of myosin minifilaments but exerts only a very weak influence on the affinity of minifilaments for F-actin. After addition of KCl the differences in the actin-stimulated Mg2+-ATPase activity disappear in a great degree; in the presence of 50 mM KCl they do not exceed 50%. It was assumed that the observed specific influence of LC2 phosphorylation on the kinetic parameters of actin-stimulated Mg2+-ATPase reaction of myosin minifilaments is due to unique properties of the minifilaments (e.g., their ability to ordered self-assembly as a result of interaction between the heads of myosin molecules) which reflect their structural peculiarities.
研究了兔骨骼肌肌球蛋白轻链-2（LC2）磷酸化对肌球蛋白微丝与F-肌动蛋白相互作用以及对微丝的肌动蛋白刺激的Mg2+-ATP酶的影响。结果表明，在没有KCl的情况下，F-肌动蛋白诱导的磷酸化LC2的肌球蛋白微丝Mg2+-ATP酶的刺激程度比未磷酸化LC2的情况高出2-4倍。LC2的磷酸化显著提高了肌球蛋白微丝的肌动蛋白刺激的Mg2+-ATP酶反应速率，但对微丝与F-肌动蛋白的亲和力影响非常微弱。加入KCl后，肌动蛋白刺激的Mg2+-ATP酶活性差异在很大程度上消失；在50 mM KCl存在下，它们不超过50%。据推测，观察到的LC2磷酸化对肌球蛋白微丝的肌动蛋白刺激的Mg2+-ATP酶反应动力学参数的特定影响是由于微丝的独特性质（例如，由于肌球蛋白分子头部之间的相互作用而有序自组装的能力），这反映了它们的结构特点。
