Stochastic Force Generation by Small Ensembles of Myosin II Motors
Stochastic Force Generation by Small Ensembles of Myosin II Motors
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DOI：
10.1103/physrevlett.108.188101
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发表时间：
2012-04-30
影响因子：
8.6
通讯作者：
Schwarz, Ulrich S.
中科院分区：
文献类型：
--
作者：
Erdmann, Thorsten;Schwarz, Ulrich S.
肌动蛋白细胞骨架中的力是由一小群非进行性肌球蛋白II马达产生的，随机效应与此高度相关。使用跨桥模型与假设的快速功率冲程动力学和等效状态之间的相等负载共享，我们推导出一个一步主方程的活动的有限大小的合奏机械耦合肌球蛋白II电机。对于恒定的外部负载，这种方法产生的占空比和力-速度关系作为合奏大小的函数的分析结果。我们发现，随机效应不能被忽略的合奏大小低于15。一步主方程也可以用于有效的计算机模拟与线性弹性外部负载，并揭示了序列的建设的力量和合奏破裂，是重组肌动球蛋白收缩性的特点。
Forces in the actin cytoskeleton are generated by small groups of nonprocessive myosin II motors for which stochastic effects are highly relevant. Using a cross-bridge model with the assumptions of fast power-stroke kinetics and equal load sharing between equivalent states, we derive a one-step master equation for the activity of a finite-sized ensemble of mechanically coupled myosin II motors. For constant external load, this approach yields analytical results for duty ratio and force-velocity relation as a function of ensemble size. We find that stochastic effects cannot be neglected for ensemble sizes below 15. The one-step master equation can be used also for efficient computer simulations with linear elastic external load and reveals the sequence of buildup of force and ensemble rupture that is characteristic for reconstituted actomyosin contractility.