在動物中,，大多數(shù)細胞在運動時利用爬行動作來遷移,，在此過程中，細胞的前端被肌動蛋白細絲的聚合所提供的力向前推進,。細胞生物學(xué)家一般假設(shè),，爬行細胞的后端隨后是由非肌肉“肌球蛋白-II”所產(chǎn)生的收縮力向前推動的,。
現(xiàn)在，對運動中的魚角膜細胞所做觀測表明,，后端收縮實際上不需要收縮力,。相反，“肌球蛋白-II”在通過肌動蛋白分解來幫助肌動蛋白網(wǎng)絡(luò)運動方面有一個直接作用,。（生物谷Bioon.com）
生物谷推薦原文出處：
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.
