Volkmann N, Amann K J, Stoilova-McPhie S, Egile C, Winter D C, Hazelwood L, Heuser J E, Li R, Pollard T D, Hanein D
The Burnham Institute, La Jolla, CA 92037, USA.
Science. 2001 Sep 28;293(5539):2456-9. doi: 10.1126/science.1063025. Epub 2001 Aug 30.
The seven-subunit Arp2/3 complex choreographs the formation of branched actin networks at the leading edge of migrating cells. When activated by Wiskott-Aldrich Syndrome protein (WASp), the Arp2/3 complex initiates actin filament branches from the sides of existing filaments. Electron cryomicroscopy and three-dimensional reconstruction of Acanthamoeba castellanii and Saccharomyces cerevisiae Arp2/3 complexes bound to the WASp carboxy-terminal domain reveal asymmetric, oblate ellipsoids. Image analysis of actin branches indicates that the complex binds the side of the mother filament, and Arp2 and Arp3 (for actin-related protein) are the first two subunits of the daughter filament. Comparison to the actin-free, WASp-activated complexes suggests that branch initiation involves large-scale structural rearrangements within Arp2/3.
由七个亚基组成的Arp2/3复合物在迁移细胞的前缘编排分支肌动蛋白网络的形成。当被威斯科特-奥尔德里奇综合征蛋白（WASp）激活时，Arp2/3复合物会从现有细丝的侧面启动肌动蛋白丝分支。对与WASp羧基末端结构域结合的卡氏棘阿米巴和酿酒酵母Arp2/3复合物进行电子冷冻显微镜和三维重建，结果显示为不对称的扁椭圆形。对肌动蛋白分支的图像分析表明，该复合物与母丝的侧面结合，而Arp2和Arp3（肌动蛋白相关蛋白）是子丝的前两个亚基。与无肌动蛋白、WASp激活的复合物相比，表明分支起始涉及Arp2/3内的大规模结构重排。
