TRAFFICKING PATHWAYS TO THE CELL SURFACE IN YEAST

酵母细胞表面的运输途径

• 批准号: 6519919
• 负责人: AMY Y CHANG
• 金额: $ 22.36万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-01 至 2004-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6519919
• 关键词: Animalia; Golgi apparatus; Saccharomyces cerevisiae; analytical ultracentrifugation; chimeric proteins; density gradient ultracentrifugation; endocytosis; fungal proteins; genetic mapping; guanine nucleotide binding protein; immunofluorescence technique; intracellular transport; membrane proteins; protein transport; site directed mutagenesis; suppressor mutations; temperature sensitive mutant; vesicle /vacuole

Membrane trafficking occurs in all eukaryotic cells as a mechanism to maintain membrane balance and organellar identity. The complexity of protein trafficking is underscored by multiple and selective pathways. During this decade there has been an explosion in the identification of proteins involved in protein transport. The approach taken in this proposal is to use combined biochemical and genetic methods in Saccharomyces cerevisiae to understand sorting and transport. Specifically, we have analyzed the trafficking of a mutant plasma membrane protein (Pma1) which fails to arrive at the cell surface. Mutant Pma1 is delivered instead to the endocytic/vacuolar pathway where it is degraded. A collection of sop (suppressor of pma1) mutants has been isolated which prevents vacuolar degradation by allowing mutant Pma1 to move to the plasma membrane. Identification of the corresponding genes has revealed novel SOP genes which are believed to regulate sorting and trafficking in the endosomal system. In Specific Aim 1, cell fractionation and indirect immunofluorescence experiments are proposed to dissect the mechanism of action of the newly-discovered SOP genes by determining whether mutant Pma1 travels from Golgi to cell surface, or endosome to surface in different sop mutants. Detection of mutant Pma1 movement from endosome to plasma membrane will help to establish the existence of a novel traffic pathway. Experiments in Specific Aim 2 focus on the role of VPS8 (identified as one of the sop mutants) in the regulation of endosomal traffic. Specific Aim 3 addresses the hypothesis that there is a novel quality control mechanism which recognizes and directs mutant proteins to the endosomal/vacuolar pathway for degradation. Experiments will test whether vacuolar delivery of mutant Pma1 is signal-mediated, and whether the novel Sop proteins are involved in a mechanism by which proteins destined for the plasma membrane are sorted from proteins destined for the endosomal/vacuolar pathway. The work described in this proposal has implications for understanding intracellular protein trafficking in health and disease.

膜转运存在于所有真核细胞中，是维持膜平衡和细胞器特性的一种机制。多条和选择性的途径突显了蛋白质贩运的复杂性。在这十年中，在识别参与蛋白质运输的蛋白质方面出现了爆炸性的增长。这项建议采取的方法是在酿酒酵母中使用生物化学和遗传学相结合的方法来了解分选和运输。具体地说，我们分析了一种未能到达细胞表面的突变质膜蛋白(Pma1)的运输。突变的Pma1被运送到内吞/空泡途径，在那里它被降解。已经分离到一组SOP(pma1抑制因子)突变体，它通过允许突变体pma1移动到质膜来防止空泡降解。对相应基因的鉴定揭示了新的SOP基因，这些基因被认为调节内体系统的分选和运输。在具体目标1中，通过细胞分离和间接免疫荧光实验来分析新发现的SOP基因的作用机制，通过确定突变体Pma1在不同的SOP突变体中是从高尔基体到细胞表面，还是从内体到表面。检测突变的Pma1从内体到质膜的运动将有助于建立一条新的运输途径的存在。特定目的2的实验重点是VPS8(被鉴定为SOP突变体之一)在调节内体运输中的作用。特定目标3解决了这样一种假设，即存在一种新的质量控制机制，该机制识别突变蛋白并将其引导到内体/空泡途径进行降解。实验将测试突变体Pma1的空泡递送是否是信号介导的，以及新的Sop蛋白是否参与了一种机制，即前往质膜的蛋白质从前往内体/空泡途径的蛋白质中分离出来。这项提案中描述的工作对于理解健康和疾病中的细胞内蛋白质贩运具有重要意义。