Hamburger Zsuzsa A, Hamburger Agnes E, West Anthony P, Weis William I
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305-5126, USA.
J Mol Biol. 2006 Feb 10;356(1):9-21. doi: 10.1016/j.jmb.2005.09.099. Epub 2005 Nov 10.
The exocyst is an evolutionarily conserved multiprotein complex required for the targeting and docking of post-Golgi vesicles to the plasma membrane. Through its interactions with a variety of proteins, including small GTPases, the exocyst is thought to integrate signals from the cell and signal that vesicles arriving at the plasma membrane are ready for fusion. Here we describe the three-dimensional crystal structure of one of the components of the exocyst, Exo70p, from Saccharomyces cerevisiae at 3.5A resolution. Exo70p binds the small GTPase Rho3p in a GTP-dependent manner with an equilibrium dissociation constant of approximately 70 microM. Exo70p is an extended rod approximately 155 angstroms in length composed principally of alpha helices, and is a novel fold. The structure provides a first view of the Exo70 protein family and provides a framework to study the molecular function of this exocyst component.
外排体是一种进化上保守的多蛋白复合物，它是高尔基体后囊泡靶向并对接至质膜所必需的。通过与多种蛋白质（包括小GTP酶）相互作用，外排体被认为整合来自细胞的信号，并表明到达质膜的囊泡已准备好融合。在此，我们描述了酿酒酵母外排体组分之一Exo70p的三维晶体结构，分辨率为3.5埃。Exo70p以GTP依赖的方式结合小GTP酶Rho3p，平衡解离常数约为70微摩尔。Exo70p是一根约155埃长的延伸杆状结构，主要由α螺旋组成，具有新颖的折叠结构。该结构首次展示了Exo70蛋白家族，并为研究该外排体组分的分子功能提供了框架。
