Structure and Function of Guanine Nucleotide Dissociation Inhibitor

描述（由申请人提供）：鸟嘌呤核苷酸解离抑制剂（GDI）在Rab蛋白的再循环中起重要作用，这是一种调节膜囊泡交通的小gtp酶。我们已经确定，Rab回收涉及Hsp90-GDI伴侣系统。本提案的主要重点是了解Hsp90伴侣复合物在Rab回收过程中介导GDI-Rab蛋白相互作用的功能的生化和分子基础。我们提出了3个具体的目标，以提供结构，分子和生化洞察GDI， Rab及其与Hsp90伴侣机制组分的顺序生理蛋白相互作用之间的结构/功能关系。我们将探讨在循环过程中rabb从脂质双分子层转移到GDI的一般假设，涉及Hsp90伴侣复合物，其方式类似于类固醇激素受体（SHR）复合物被Hsp90伴侣复合物结合类固醇激素。Specific Aim 1将继续扩大我们的结构研究，以确定GDI功能的分子基础。这些研究将包括确定β和δ GDI异构体的结构，确定从牛脑分离的天然α GDI- rab3a - gg复合物的结构，以及确定α GDI- hsp90伴侣复合物的结构。特异性目标2将应用生化方法来识别和表征GDI与Hsp90伴侣复合物组分相互作用的基础。这些研究将利用对Hsp90伴侣复合物在调节SHR和信号激酶途径中的作用的广泛了解。特异性Aim 3将采取分子方法来确定GDI、Rab和Hsp90伴侣复合物之间蛋白质相互作用的基础。这三个目标将极大地促进我们对GDI和Rab gtp酶在膜运输中的一般作用的基本理解，这是当代细胞生物学的一个高度感兴趣的领域。鉴于GDI和Rab在智力迟钝、造血谱系疾病、眼病和与Hsp90调节的信号通路变化相关的细胞增殖（癌症）中的作用，它们将为更广泛的疾病提供见解。

DESCRIPTION (provided by applicant): Guanine nucleotide dissociation inhibitor (GDI) plays an essential role in the recycling of Rab proteins, small GTPases that regulate membrane vesicle traffic. We have established that Rab recycling involves a Hsp90-GDI chaperone system. The principle focus of this proposal is to understand the biochemical and molecular basis for the function of the Hsp90 chaperone complex in mediating GDI-Rab protein interaction during Rab recycling.We propose 3 specific aims to provide structural, molecular and biochemical insight into the structure/function relationships between GDI, Rab and their sequential physiological protein interactions with components of the Hsp90 chaperone machinery. We will explore the general hypothesis that transfer of Rab from the lipid bilayer to GDI during recycling involves a Hsp90 chaperone complex in an analogous fashion to the manner in which steroid hormone receptors (SHR) complexes are primed for steroid hormone binding by the Hsp90 chaperone complex. Specific Aim 1 will continue to expand our structural studies to determine the molecular basis of GDI function. These studies will include determining the structure of beta and delta GDI isoforms, determining the structure of the native alpha GDI-Rab3A-GG complex isolated from bovine brain, and determining structure(s) of alpha GDI-Hsp90 chaperone complexes. Specific Aim 2 will apply biochemical approaches to identify and characterize the basis for the interaction of GDI with components of the Hsp90 chaperone complex. These studies will take advantage of the extensive knowledge of the role of the Hsp90 chaperone complexes in regulation of SHR and signaling kinase pathways. Specific Aim 3 will take a molecular approach to identify the basis for protein interactions between GDI, Rab and the Hsp90 chaperone complex. These three aims will contribute significantly to advancing our basic understanding of the general role of GDI and Rab GTPases in membrane transport, an area of high interest to contemporary cell biology. They will provide insight into a broad spectrum of diseases given the role of GDI and Rab in mental retardation, diseases of hematopoietic lineage, eye disease and cell proliferation (cancer) related to changes in Hsp90 regulated signaling pathways.