Alteration of cross-bridge kinetics by myosin light chain phosphorylation in rabbit skeletal muscle: implications for regulation of actin-myosin interaction.
Alteration of cross-bridge kinetics by myosin light chain phosphorylation in rabbit skeletal muscle: implications for regulation of actin-myosin interaction.
复制标题
兔骨骼肌中肌球蛋白轻链磷酸化改变跨桥动力学：对肌动蛋白-肌球蛋白相互作用调节的影响。
DOI：
10.1073/pnas.87.1.414
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发表时间：
1990
影响因子：
11.1
通讯作者：
Stull,JT
中科院分区：
文献类型：
--
作者：
Sweeney,HL;Stull,JT
肌球蛋白轻链磷酸化在可渗透性骨骼肌纤维增加等长收缩力和力的生产率在次最大水平的钙激活;肌球蛋白轻链磷酸化可能是基础的增加率和程度的生产力与等长收缩增强在完整的纤维。为了了解肌球蛋白轻链磷酸化表现出这些作用的机制，我们测量了等长力，等长刚度，等张缩短后等长力重建率，和等长ATP酶活性透化兔腰肌纤维。这些测量是在存在和不存在肌球蛋白轻链磷酸化的情况下在引起各种水平激活的钙浓度范围内进行的。采用Brenner [Brenner，B.等人（1988）Proc. Acad. Sci. USA 85，3265-3269]。结果表明，肌球蛋白轻链磷酸化通过一种单一的机制，即通过增加描述从非力产生交叉桥到力产生状态（fapp）的转变的速率常数，对横纹肌的力产生和力重建的等长速率产生影响。反向速率常数gapp不受磷酸化的影响，循环交叉桥的数目也是如此。由于钙和肌球蛋白轻链磷酸化增加fapp，被认为是可能性，fapp的调制可能代表了一个一般的机制，调节肌动蛋白-肌球蛋白系统的力量。
Myosin light chain phosphorylation in permeable skeletal muscle fibers increases isometric force and the rate of force production at submaximal levels of calcium activation; myosin light chain phosphorylation may underlie the increased rate and extent of force production associated with isometric twitch potentiation in intact fibers. To understand the mechanism by which myosin light chain phosphorylation manifests these effects, we have measured isometric force, isometric stiffness, rate of isometric force redevelopment after isotonic shortening, and isometric ATPase activity in permeabilized rabbit psoas muscle fibers. These measurements were made in the presence and absence of myosin light chain phosphorylation over a range of calcium concentrations that caused various levels of activation. The results were analyzed with a two-state cross-bridge cycle model as suggested by Brenner [Brenner, B. (1988) Proc. Natl. Acad. Sci. USA 85, 3265-3269]. The results indicate that myosin light chain phosphorylation exerts its effect on force generation and the isometric rate of force redevelopment in striated muscle through a single mechanism, namely, by increasing the rate constant describing the transition from non-force-generating cross-bridges to force-generating states (fapp). gapp, the reverse rate constant, is unaffected by phosphorylation as are the number of cycling cross-bridges. Since both calcium and myosin light chain phosphorylation increase fapp, the possibility is considered that modulation of fapp may represent a general mechanism for regulating force in actin-myosin systems.