IRSp53 is an essential intermediate between Rac and WAVE in the regulation of membrane ruffling
IRSp53 is an essential intermediate between Rac and WAVE in the regulation of membrane ruffling
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DOI：
10.1038/35047107
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发表时间：
2000-12-07
期刊：
影响因子：
64.8
通讯作者：
Takenawa, T
中科院分区：
文献类型：
--
作者：
Miki, H;Yamaguchi, H;Takenawa, T
神经Wiskott-Aldrich综合征蛋白（N-WASP）（1）通过Arp 2/3复合物刺激快速肌动蛋白聚合，在几种细胞内事件中发挥作用，包括丝状伪足形成（2）、囊泡运输（3）以及弗氏志贺氏菌（4，5）和牛痘病毒（6）的运动。N-WASP受Cdc 42的直接结合调节（参考文献7，8），Cdc 42暴露N-WASP中激活Arp 2/3复合物的结构域（2，9）。WASP相关蛋白WAVE/ Scar在pac诱导的膜皱褶中起作用（10，11）;然而，pac不直接与WAVE结合（10），这就提出了WAVE如何受Rac调节的问题。在这里，我们证明了IRSp 53，一种功能未知的胰岛素受体底物（12），是pac和WAVE之间的“缺失环节”。活化的Rac与IRSp 53的氨基端结合，IRSp 53的羧基端Src-同源性-3结构域与WAVE结合形成三分子复合物。从异位表达的研究中，我们发现IRSp 53是Rac诱导膜皱褶所必需的，可能是因为它招募WAVE，WAVE刺激Arp 2/3复合物介导的肌动蛋白聚合。
Neural Wiskott-Aldrich syndrome protein (N-WASP)(1) functions in several intracellular events including filopodium formation(2), vesicle transport(3) and movement of Shigella frexneri(4,5) and vaccinia virus(6), by stimulating rapid actin polymerization through the Arp2/3 complex. N-WASP is regulated by the direct binding of Cdc42 (refs 7, 8), which exposes the domain in N-WASP that activates the Arp2/3 complex(2,9). A WASP-related protein, WAVE/ Scar, functions in pac-induced membrane ruffling(10,11); however, pac does not bind directly to WAVE(10), raising the question of how WAVE is regulated by Rac. Here we demonstrate that IRSp53, a substrate for insulin receptor(12) with unknown function, is the 'missing link' between pac and WAVE. Activated Rac binds to the amino terminus of IRSp53, and carboxy-terminal Src-homology-3 domain of IRSp53 binds to WAVE to form a trimolecular complex. From studies of ectopic expression, we found that IRSp53 is essential for Rac to induce membrane ruffling, probably because it recruits WAVE, which stimulates actin polymerization mediated by the Arp2/3 complex.