在动物中，大多数细胞在运动时利用爬行动作来迁移，在此过程中，细胞的前端被肌动蛋白细丝的聚合所提供的力向前推进。细胞生物学家一般假设，爬行细胞的后端随后是由非肌肉“肌球蛋白-II”所产生的收缩力向前推动的。
现在，对运动中的鱼角膜细胞所做观测表明，后端收缩实际上不需要收缩力。相反，“肌球蛋白-II”在通过肌动蛋白分解来帮助肌动蛋白网络运动方面有一个直接作用。（生物谷Bioon.com）
生物谷推荐原文出处：
Nature doi:10.1038/nature08994
Myosin II contributes to cell-scale actin network treadmilling through network disassembly
Cyrus A. Wilson,Mark A. Tsuchida,Greg M. Allen,Erin L. Barnhart,Kathryn T. Applegate,Patricia T. Yam,Lin Ji,Kinneret Keren,Gaudenz Danuser& Julie A. Theriot
Crawling locomotion of eukaryotic cells is achieved by a process dependent on the actin cytoskeleton1: protrusion of the leading edge requires assembly of a network of actin filaments2, which must be disassembled at the cell rear for sustained motility. Although ADF/cofilin proteins have been shown to contribute to actin disassembly3, it is not clear how activity of these locally acting proteins could be coordinated over the distance scale of the whole cell. Here we show that non-muscle myosin II has a direct role in actin network disassembly in crawling cells. In fish keratocytes undergoing motility, myosin II is concentrated in regions at the rear with high rates of network disassembly. Activation of myosin II by ATP in detergent-extracted cytoskeletons results in rear-localized disassembly of the actin network. Inhibition of myosin II activity and stabilization of actin filaments synergistically impede cell motility, suggesting the existence of two disassembly pathways, one of which requires myosin II activity. Our results establish the importance of myosin II as an enzyme for actin network disassembly; we propose that gradual formation and reorganization of an actomyosin network provides an intrinsic destruction timer, enabling long-range coordination of actin network treadmilling in motile cells.
