Signal Transduction Via Receptors and G proteins

描述(由申请人提供)：调节激素和其他细胞外刺激的一个主要信号范例是细胞表面受体使用异源三聚体G蛋白。除了直接调节细胞内产生第二信使的细胞内酶外，这些受体/G蛋白通路还影响单体GTP酶Ras超家族中的几个成员的活动。这个家族的成员，如Ras和Rho蛋白，调节细胞的生长、分化、形状和黏附。P115蛋白被异源三聚体G13蛋白激活后，通过刺激Rho上的GTP交换，将两个G蛋白家族直接连接起来。激素--受体--&gt；？G13--&gt；p115 Rhogef--&gt；Rho。这项建议继续在体外检查这一途径的组件之间的调节机制，并试图明确定义蛋白质在细胞调节中的生理作用。建议的研究包括尝试确定调节复合体的结构，突变分析和荧光方法来识别机制，亲和力方法来确定该途径的其他成分，以及下调内源蛋白以确定功能特异性。开发嵌合的G13pha蛋白和确定激活G蛋白的受体非依赖途径的倡议将有助于机制研究，并开辟新的视角来确定G13在众多细胞途径的调节中的作用。已知p115 Rhogef及其同系物的突变是致癌的。发展需要G13。进展将增加我们对这些调控生长、分化和细胞运动的关键途径的理解。这将有助于更好地理解各种激素所赋予的调节以及这些蛋白质在细胞功能障碍中的作用。

DESCRIPTION (provided by applicant): A major signaling paradigm for modulation of hormonal and other extracellular stimuli is the use of heterotrimeric G proteins by cell surface receptors. Besides direct regulation of intracellular enzymes that produce intracellular second messengers, these receptor/G protein pathways influence the action of several members of the Ras superfamily of monomeric GTPases. Members of this family, such as the Ras and Rho proteins, regulate cellular growth, differentiation, shape and adhesion. P115 RhoGEF can directly connect the two families of G proteins by stimulating exchange of GTP on Rho when activated by the heterotrimeric G13 protein. Hormone --> Receptor --> ? G13 --> p115RhoGEF --> Rho. This proposal continues examination of the regulatory mechanisms among components of this pathway in vitro and attempts to clearly define the physiological role of proteins in cellular regulation. Proposed studies include attempts to determine structures of regulatory complexes, mutational analysis and fluorescent approaches to discern mechanisms, affinity approaches to identify other components of the pathway, and down-regulation of the endogenous protein to determine functional specificity. Initiatives to develop a chimeric G13alpha protein and define receptor independent pathways for activating the G protein will aid mechanistic studies as well as open new perspectives to determine the role of G13 in the modulation of numerous cellular pathways. Mutations in p115 RhoGEF and its homologues are known to be oncogenic. G13 is required for development. Progress will increase our understanding of these key pathways in regulating growth, differentiation and cell motility. This will help to better understand the regulation imparted by a variety of hormones and the contribution of these proteins to cellular dysfunction.