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主要信号范式是细胞表面受体使用异源三聚体G蛋白。除了直接调控产生胞内第二信使的胞内酶外，这些受体/G蛋白途径还影响了单体gtpase Ras超家族的几个成员的作用。该家族的成员，如Ras和Rho蛋白，调节细胞生长、分化、形状和粘附。P115 RhoGEF被异源三聚体G13蛋白激活后，通过刺激GTP在Rho上的交换，直接连接两个G蛋白家族。激素——>受体——> ？G13—> p115RhoGEF—> Rho。本研究继续在体外研究这一途径各组成部分之间的调控机制，并试图明确界定蛋白质在细胞调控中的生理作用。拟议的研究包括尝试确定调节复合物的结构，突变分析和荧光方法来识别机制，亲和力方法来识别途径的其他组成部分，以及下调内源性蛋白来确定功能特异性。开发嵌合g13α蛋白和确定激活G蛋白的受体独立途径的举措将有助于机制研究，并为确定G13在许多细胞通路调节中的作用开辟新的视角。p115 RhoGEF及其同系物的突变已知是致癌的。发展需要G13。进展将增加我们对这些调节生长、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的调节以及这些蛋白质对细胞功能障碍的贡献。

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.