YPTL GTPASE AND VESICULAR TRANSPORT

描述：阐明了蛋白质被分选成 正确的分隔区是我们理解细胞生长的基础。 细胞内区室之间的蛋白质转运由 膜囊泡，GTP酶的rab/Ypt家族在膜囊泡中起主要作用。 调节这些囊泡在所有真核细胞中的靶向。 的 该项目的长期目标是了解囊泡运输如何 操作以及rab/Ypt GTP在其 调控 囊泡融合的基础机制是高度保守的 酵母和人之间的关系。这项建议特别针对的功能， 以面包酵母的Ypt 1为模型，研究了酵母分泌型Ypt GTP酶。 拟议的研究将集中在与Ypt GTP酶相互作用的蛋白质上 以及它们作为效应器或调节器发挥作用的机制。 现有的以及新发现的基因，将检查其作用 在蛋白质转运分析潜在的分泌缺陷突变体，和 研究其产物的细胞内定位。 过表达 研究将被用来区分假定的调节因子， Ypt 1的核苷酸循环，从那些作为Ypt 1效应物起作用的核苷酸循环， 这通常不影响这种循环。 这些基因将用于 解决以下问题：1）效应蛋白的作用是什么 Ypt GTP酶的研究 Rab蛋白，像其他ras相关的GTP酶，被认为是 通过调节下游效应子发挥作用， GTP依赖性的方式，将信号从GTP结合形式传递到 膜对接和/或融合装置。 为了确定确切的机制 Ypt 1效应子的功能，这些基因中突变体的行为 将检查visicle出芽，靶向，脱壳或 融合，以及它们与Ypt 1相互作用的性质。 2)有什么作用 调节Ypt GTP酶核苷酸循环的辅助因子？ GTP和GDP结合形式之间的循环，由附件促进 因素，被认为是至关重要的rab功能。 然而， 关于这些因素如何找到他们的rab目标，他们如何促进 核苷酸交换和水解。 将对推定的监管机构进行测试 这些活动。 解决有关其特异性的问题， 作用机制，它们与Ypt和其他蛋白的相互作用， 将在体内和体外检查分泌功能。 最后， 将探索外泌Ypt蛋白本身之间的相互作用。

DESCRIPTION: Elucidation of the mechanism by which proteins are sorted into the correct compartments is fundamental to our understanding of cell growth. Protein transport between intracellular compartments is mediated by membranous vesicles, and the rab/Ypt family of GTPases plays a major role in regulating the targeting of these vesicles in all eukaryotic cells. The long term goal of the project is to understand how vesicular transport operates and the specific role(s) that rab/Ypt GTPases have in its regulation. Mechanisms that underlie vesicle fusion are highly conserved between yeast and man. This proposal specifically addreses the function of Ypt GTPases in secretion, using Ypt1 of baker's yeast as a model. The proposed research will focus on proteins that interact with Ypt GTPases and the mechanisms by which they function as effectors or regulators. Existing as well as newly identified genes, will be examined for their role in protein transport analyzing potential secretory defects in mutants, and studying intracellular localization of their products. Overexpression studies will be used to distinguish putative regulators that modulate nucleotide cycling of Ypt1, from those that funciton as Ypt1 effectors, which typically do not affect this cycling. These genes will be used to address the following questions: 1) What are the roles of effector proteins of Ypt GTPases? Rab proteins, like other ras-related GTPases, are believed to function through the regulation of downstream effectors in a GTP-dependent manner, to transmit a signal from the GTP-bound form to the membrane docking and/or fusion apparatus. To determine the exact mechanism by which Ypt1 effectors function, the behavior of mutants in these genes will be examined with respect to visicle budding, targeting, uncoating or fusion, and the nature of their interaction with Ypt1. 2) What is the role of accessory factors that regulate nucleotide cycling of Ypt GTPases? Cycling between the GTP- and GDP-bound forms, facilitated by accessory factors, is considered crucial for rab function. However, little is known regarding how these factors find their rab targets of how they facilitate nucleotide exchange and hydrolysis. Putative regulators will be tested for these activities. To resolve issues concerning their spoecificity and mechanism of action, their interactions with Ypt and other proteins that funciton in secretion will be examined in vivo and in vitro. Finally, interaction among exocytic Ypt proteins themselves will be explored.