Welch M D, DePace A H, Verma S, Iwamatsu A, Mitchison T J
Department of Cellular and Molecular Pharmacology, University of California, San Francisco, California 94143-0450, USA.
J Cell Biol. 1997 Jul 28;138(2):375-84. doi: 10.1083/jcb.138.2.375.
The Arp2/3 protein complex has been implicated in the control of actin polymerization in cells. The human complex consists of seven subunits which include the actin related proteins Arp2 and Arp3, and five others referred to as p41-Arc, p34-Arc, p21-Arc, p20-Arc, and p16-Arc (p omplex). We have determined the predicted amino acid sequence of all seven subunits. Each has homologues in diverse eukaryotes, implying that the structure and function of the complex has been conserved through evolution. Human Arp2 and Arp3 are very similar to family members from other species. p41-Arc is a new member of the Sop2 family of WD (tryptophan and aspartate) repeat-containing proteins and may be posttranslationally modified, suggesting that it may be involved in regulating the activity and/or localization of the complex. p34-Arc, p21-Arc, p20-Arc, and p16-Arc define novel protein families. We sought to evaluate the function of the Arp2/3 complex in cells by determining its intracellular distribution. Arp3, p34-Arc, and p21-Arc were localized to the lamellipodia of stationary and locomoting fibroblasts, as well to Listeria monocytogenes assembled actin tails. They were not detected in cellular bundles of actin filaments. Taken together with the ability of the Arp2/3 complex to induce actin polymerization, these observations suggest that the complex promotes actin assembly in lamellipodia and may participate in lamellipodial protrusion.
Arp2/3蛋白复合体与细胞中肌动蛋白聚合的调控有关。人类复合体由七个亚基组成，其中包括肌动蛋白相关蛋白Arp2和Arp3，以及另外五个被称为p41-Arc、p34-Arc、p21-Arc、p20-Arc和p16-Arc（p复合体）的亚基。我们已经确定了所有七个亚基的预测氨基酸序列。每个亚基在不同的真核生物中都有同源物，这意味着该复合体的结构和功能在进化过程中得以保留。人类的Arp2和Arp3与其他物种的家族成员非常相似。p41-Arc是含WD（色氨酸和天冬氨酸）重复序列的Sop2家族的新成员，可能经过翻译后修饰，这表明它可能参与调节复合体的活性和/或定位。p34-Arc、p21-Arc、p20-Arc和p16-Arc定义了新的蛋白质家族。我们试图通过确定其细胞内分布来评估Arp2/3复合体在细胞中的功能。Arp3、p34-Arc和p21-Arc定位于静止和成纤维细胞运动的板状伪足，以及单核细胞增多性李斯特菌组装的肌动蛋白尾。在肌动蛋白丝的细胞束中未检测到它们。结合Arp2/3复合体诱导肌动蛋白聚合的能力，这些观察结果表明该复合体促进板状伪足中的肌动蛋白组装，并可能参与板状伪足的突出。
