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arXiv · 1202.3038

Stochastic force generation by small ensembles of myosin II motors

Thorsten Erdmann·Ulrich S. Schwarz
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Abstract

Forces in the actin cytoskeleton are generated by small groups of non-processive myosin II motors for which stochastic effects are highly relevant. Using a crossbridge model with the assumptions of fast powerstroke 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 build-up of force and ensemble rupture that is characteristic for reconstituted actomyosin contractility.

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Thorsten Erdmann, Ulrich S. Schwarz. 2012-02-14. Stochastic force generation by small ensembles of myosin II motors. https://doi.org/10.1103/physrevlett.108.188101

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