THE TRANSITIONAL ER-GOLGI SYSTEM IN BUDDING YEASTS

我们的目标是了解高尔基体堆栈是如何产生的。 一个有吸引力的模型是，新的高尔基体元件产生的COPII运输囊泡，在过渡ER（tER）网站。 因此，表征tER对于了解高尔基体至关重要。 例如，高尔基体在芽殖酵母中的分布似乎是tER分布的结果。 在酿酒酵母中，高尔基体池分散在整个细胞质中，整个ER作为tER发挥功能;而在巴斯德毕赤酵母中，连贯的高尔基体堆位于离散的tER位点旁边。 这两种酵母将通过遗传学，生物化学和显微镜的组合进行分析，以阐明定义tER-高尔基体系统的机制。 我们的具体目的是：（1）刻画S。高尔基体遗传缺陷的酿酒酵母突变体。 这项研究将测试的想法，高尔基体遗传是一个副产品的ER遗传。 (2)分离具有异常tER组织的巴斯德毕赤酵母突变体。 这些突变体将引导我们找到定义tER位点的蛋白质，并揭示高尔基体分布是否确实是tER分布的结果。 (3)确定巴斯德毕赤酵母Sec 12 p如何定位于tER位点。 由于Sec 12 p被认为是COPII组装途径的“主调节因子”，因此分析该蛋白的定位机制将有助于深入了解tER的形成。异常的高尔基体功能是许多疾病的病原体，包括癌症以及各种遗传性和自身免疫性疾病。 这些疾病的治疗需要对建立和维持高尔基体组织的过程有细胞生物学的理解。 我们的工作旨在阐明高尔基体生物发生的这些基本原则。

Our goal is to understand how Golgi stacks are generated. An attractive model is that new Golgi elements arise from the COPII transport vesicles that are produced at transitional ER (tER) sites. Thus, characterizing the tER will be crucial for understanding the Golgi. For example, Golgi distribution in budding yeasts seems to be a consequence of tER distribution. In Saccharomyces cerevisiae, Golgi cisternae are dispersed throughout the cytoplasm and the entire ER functions as tER; whereas in Pichia pastoris, coherent Golgi stacks are located next to discrete tER sites. These two yeasts will be analyzed through a combination of genetics, biochemistry and microscopy to elucidate the mechanisms that define the tER-Golgi system. Our Specific Aims are: (1) To characterize S. cerevisiae mutants defective in Golgi inheritance. This study will test the idea that Golgi inheritance is a byproduct of ER inheritance. (2) To isolate P. pastoris mutants with abnormal tER organization. Such mutants will lead us to the proteins that define tER sites, and will reveal whether Golgi distribution is indeed a consequence of tER distribution. (3) To determine how P. pastoris Sec12p is localized to tER sites. Because Sec12p is thought to be the "master regulator" of the COPII assembly pathway, analyzing the localization mechanism of this protein will yield insights into tER formation. Abnormal Golgi function is a causative agent in many diseases, including cancer as well as various inherited and autoimmune diseases. Treatment of these diseases will require a cell biological understanding of the processes that establish and maintain Golgi organization. Our work aims to elucidate these basic principles of Golgi biogenesis.