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传导范例是通过细胞表面受体使用异源三聚体G蛋白。除了直接调节产生细胞内第二信使的细胞内酶外，这些受体/G蛋白途径还影响单体GTP酶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在被异源三聚体G13蛋白激活时，通过刺激Rho上的GTP交换而直接连接两个G蛋白家族。 激素受体G13 --> p115RhoGEF --> Rho。该建议继续检查在体外的这一途径的组件之间的调节机制，并试图清楚地定义蛋白质在细胞调节中的生理作用。 拟议的研究包括尝试确定调控复合物的结构，突变分析和荧光方法来辨别机制，亲和方法来识别途径的其他组分，以及下调内源性蛋白质以确定功能特异性。开发嵌合G13 α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，并开辟新的视角来确定G13在众多细胞途径调节中的作用。 已知p115 RhoGEF及其同源物中的突变是致癌的。G13是发展所必需的。 这些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。 这将有助于更好地了解各种激素的调节作用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.