NEW YEAST MUTANTS IN POSTGOLGI TRANSPORT

先前的遗传筛选已经确定酵母分泌突变体具有 在分泌途径的沿着不同点阻断蛋白质运输。而 这些突变体最有可能阻止所有货物的运输， 后高尔基体囊泡运输独特的货物到质膜， 最近被定性。这项提议旨在分离新的突变体 在这些囊泡种类中的仅一种的运输中被阻断。一 策略涉及一种选择方案，其中分泌块将 让细胞生长。虽然这种方法很可能只识别非- 必要的基因，使用选择作为初始步骤， 促进突变体分离。第二次筛选利用K/28杀手毒素作为 一种用于鉴定必需的条件突变的分泌标记物， 分泌K/28和途径中其他货物所需的基因 运送这种毒素 更好地理解囊泡介导的转运机制 从高尔基体到质膜需要识别 这一过程中涉及的关键组成部分，以及 在所提出的筛选中分离的突变体应该对此做出很大贡献 端这些突变体，以及一种新的体外芽殖试验在酵母中， 后期分泌囊泡形成的生化分析，将 为后续的生物化学和遗传学研究提供了强有力的工具。

Previous genetic screens have identified yeast secretory mutants have block protein traffic at various points along the secretory pathway. While these mutants most likely block the transport of all cargo, two classes of post-Golgi vesicles transporting unique cargo to the plasma membrane have been recently characterized. This proposal aims to isolate new mutants blocked in the transport of only one of these vesicle species. One strategy involves a selection scheme in which a secretory block would allow cells to grow. While this method will most likely identify only non- essential genes, the use of a selection as an initial step should greatly facilitate mutant isolation. A second screen utilizes K/28 killer toxin as a secretory marker for identifying conditional mutations in essential genes required for the secretion of K/28 and other cargo in the pathway transporting this toxin. A better understanding of the mechanisms of vesicle-mediated transport from the Golgi to the plasma membrane will require the identification of the key components involved in this process, and characterization of the mutants isolated in the proposed screens should greatly contribute to this end. These mutants, as well as a new in vitro budding assay in yeast for the biochemical analysis of the formation of late secretory vesicles, will provide powerful tools for subsequent biochemical and genetic studies.