Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA.
Mol Biol Cell. 2010 Feb 15;21(4):562-71. doi: 10.1091/mbc.e09-03-0217. Epub 2009 Dec 16.
ARFs are small GTPases that regulate vesicular trafficking, cell shape, and movement. ARFs are subject to extensive regulation by a large number of accessory proteins. The many different accessory proteins are likely specialized to regulate ARF signaling during particular processes. ARNO/cytohesin 2 is an ARF-activating protein that promotes cell migration and cell shape changes. We report here that protein-protein interactions mediated by the coiled-coil domain of ARNO are required for ARNO induced motility. ARNO lacking the coiled-coil domain does not promote migration and does not induce ARF-dependent Rac activation. We find that the coiled-coil domain promotes the assembly of a multiprotein complex containing both ARNO and the Rac-activating protein Dock180. Knockdown of either GRASP/Tamalin or IPCEF, two proteins known to bind to the coiled-coil of ARNO, prevents the association of ARNO and Dock180 and prevents ARNO-induced Rac activation. These data suggest that scaffold proteins can regulate ARF dependent processes by biasing ARF signaling toward particular outputs.
ARF 是一种小 GTPase，可调节囊泡运输、细胞形态和运动。ARF 受到大量辅助蛋白的广泛调节。许多不同的辅助蛋白可能专门用于在特定过程中调节 ARF 信号。ARNO/cytohesin 2 是一种 ARF 激活蛋白，可促进细胞迁移和细胞形态变化。我们在此报告，由 ARNO 的卷曲螺旋结构域介导的蛋白-蛋白相互作用是 ARNO 诱导运动所必需的。缺乏卷曲螺旋结构域的 ARNO 不会促进迁移，也不会诱导 ARF 依赖性 Rac 激活。我们发现，卷曲螺旋结构域促进了一个包含 ARNO 和 Rac 激活蛋白 Dock180 的多蛋白复合物的组装。敲低已知与 ARNO 的卷曲螺旋结合的两种蛋白 GRASP/Tamalin 或 IPCEF，可阻止 ARNO 和 Dock180 的结合，并阻止 ARNO 诱导的 Rac 激活。这些数据表明，支架蛋白可以通过将 ARF 信号偏向特定输出，从而调节 ARF 依赖性过程。
