Orlova A, Egelman E H
Department of Cell Biology and Neuroanatomy, University of Minnesota Medical School, Minneapolis 55455.
J Mol Biol. 1993 Jul 20;232(2):334-41. doi: 10.1006/jmbi.1993.1393.
The mechanical properties of F-actin are very significant, given the central structural role played by actin filaments within muscle and the cytoskeleton. We have determined that actin can exist in a state that has a fourfold increase in flexibility over normal F-actin, and nucleotide. Three-dimensional reconstructions from electron micrographs suggest that this increased flexibility arises from a rotation of subdomain-2, the smallest subdomain, of the actin subunit. The modulation of actin's flexibility by Ca2+ and Mg2+ may have important physiological consequences within the cell. Further, since it has been shown that myosin-decorated actin filaments are more flexible than pure F-actin, it is possible that myosin induces this more flexible state in actin.
鉴于肌动蛋白丝在肌肉和细胞骨架中所起的核心结构作用，F-肌动蛋白的力学性能非常重要。我们已经确定，肌动蛋白可以处于一种比正常F-肌动蛋白和核苷酸的柔韧性增加四倍的状态。电子显微镜图像的三维重建表明，这种增加的柔韧性源于肌动蛋白亚基最小的亚结构域2的旋转。Ca2+和Mg2+对肌动蛋白柔韧性的调节可能在细胞内具有重要的生理意义。此外，由于已经表明肌球蛋白修饰的肌动蛋白丝比纯F-肌动蛋白更具柔韧性，因此肌球蛋白有可能在肌动蛋白中诱导出这种更具柔韧性的状态。
