FUNCTION OF THE RAS RELATED RAL PROTEINS

本提案的总体目标是更好地了解 Ras相关Ral蛋白的功能。RalA和RalB存在于 胞质囊泡的膜，包括那些参与内吞作用的囊泡 和胞吐作用，尽管相当大比例的蛋白质也 与细胞膜相连。作为Ras超家族的成员， GTP酶，Ral蛋白在活性GTP结合和非活性GDP之间循环 约束状态。它们在细胞中被激活， 核苷酸交换因子，Ral-GDS和RGL，并被灭活， 结合到一个独特的谷氨酰胺活化蛋白，Ral-GAP。我们最近 表明Ras可以通过结合并激活其受体来激活细胞中的Ral， 交换因子Ral-GDS。因此，Ral-GDS和Ral的活化代表了一种新的活化。 新发现的Ras下游信号通路。学习Ral 功能可能有助于我们理解Ras蛋白如何影响细胞 分化细胞的增殖、分化和表达 功能 我们最近还确定了两个下游目标， Ral蛋白的不同区域。磷脂酶D（PLD） 由Ras信号通路和Ral结合蛋白刺激 1（RalBP 1），一种新的Cdc 42和Rac GTP酶的GAP。 这项建议的重点是Ral如何被调控的分子细节， Ras和可能的其他上行信号。它还研究了功能 PLD和RalBP 1，以及这两种信号分子是如何被调节的。 拉尔最后，本提案中描述的实验将确定 这种新发现的Ras/Ral的重要功能之一 信号传导途径是调节细胞分泌和/或内吞作用。

The overall goal of this proposal is to gain a better understanding of the function of Ras-related Ral proteins. RalA and RalB are present in the membranes of cytoplasmic vesicles including those involved in endocytosis and exocytosis, although a significant proportion of the proteins is also associated with the plasma membrane. As members of the Ras superfamily of GTPases, Ral proteins cycle between the active GTP bound and inactive GDP bound states. They are activated in cells upon binding to unique nucleotide exchange factors, Ral-GDS and RGL, and are inactivated by binding to a unique GTPase activating protein, Ral-GAP. We have recently shown that Ras can activate Ral in cells by binding to and activating its exchange factor Ral-GDS. Thus activation of Ral-GDS and Ral represents a newly identified downstream signalling pathway from Ras. Studying Ral function may aid in our understanding of how Ras proteins influence cell proliferation, differentiation and expression of differentiated cell function. We have also recently identified two downstream targets that interact with distinct regions of Ral proteins. These include a phospholipase D (PLD) that is stimulated by the Ras signalling pathway and Ral binding protein 1 (RalBP1), a novel GAP for Cdc42 and Rac GTPases. This proposal focuses on the molecular details of how Ral is regulated by Ras and possibly other upstream signals. It also investigates the function of PLD and RalBP1, and how these two signalling molecules are regulated by Ral. Finally, the experiments described in this proposal will determine whether one of the important functions of this newly identified Ras/Ral signalling pathway is to modulate cellular secretion and/or endocytosis.