YEAST LATE GOLGI MEMBRANE PROTEIN RETENTION

本建议中概述的研究是针对一般 关于膜蛋白如何正确分类和定位的问题， 特殊的真核细胞器。的生物发生和维持 细胞器，一个依赖于正确定位的知之甚少的过程 以及膜蛋白的保留对于细胞的正常功能至关重要。 此外，几种人类疾病（例如囊性纤维化和家族性疾病） 高胆固醇血症）是由于膜的分选缺陷引起的 proteins.虽然已经鉴定了许多膜蛋白分选事件， 在真核细胞中，我们对负责 识别和定位膜蛋白到正确的细胞 车厢 该提案描述了一种多方面的方法来描述 高尔基体保留其固有高尔基膜的机制 proteins.该分析已在酵母S.酿酒酵母， 因为这种真核生物很容易被遗传学所控制。末 高尔基体酶，二肽氨基肽酶（DPAP）A，已被证明是 在其胞质结构域中包含保留信号， 必要和充分的本地化在高尔基体。在 为了识别识别这种信号的细胞机制， 保留了高尔基体中的DPAP A，已经开发了一种遗传筛选， 鉴定不能适当保留其高尔基体膜突变体 proteins.迄今为止鉴定的grd（高尔基体保留缺陷）突变体 分为10个互补组。阐明《公约》的作用 单个grd基因产物在高尔基体膜蛋白保留中的作用 有望阐明高尔基体保留机制，特别是可能 为识别DPAP A保留信号提供基础 受体的独立的遗传学和生物化学方法也将被 追求更直接地集中于识别保留信号 受体的通过实验确定是否发生保留 还将进行从后高尔基体隔室的回收。的 这些研究的结果应该有助于阐明酵母的机制， 高尔基体膜蛋白质的保留和增加显着我们的整体 膜蛋白分选知识。

The research outlined in this proposal is directed towards the general question of how membrane proteins are properly sorted and localized to specific eukaryotic cellular organelles. The biogenesis and maintenance of organelles, a poorly understood process dependent on correct localization and retention of membrane proteins, is critical for proper cell function. In addition, several human diseases (e.g. cystic fibrosis and familial hypercholesterolaemia) arise due to defects in the sorting of membrane proteins. While many membrane protein sorting events have been identified in eukaryotic cells, little is known of the machinery responsible for recognizing and localizing membrane proteins to the correct cellular compartment. This proposal describes a multi-faceted approach to characterize the mechanism by which the Golgi apparatus retains its resident Golgi membrane proteins. This analysis has been conducted in the yeast, S. cerevisiae, because this eukaryotic organism is easily amenable to genetics. The late Golgi enzyme, dipeptidyl aminopeptidase (DPAP) A, has been shown to contain a retention signal it its cytoplasmic domain which is both necessary and sufficient for its localization in the Golgi apparatus. In order to identify the cellular machinery that recognizes this signal and retains DPAP A in the Golgi, a genetic screen has been developed to identify mutants which fail to properly retain their Golgi membrane proteins. The grd (Golgi retention defective) mutants identified thus far fall into 10 complementation groups. The elucidation of the role of the individual grd gene products in the retention of Golgi membrane proteins promises to illuminate the Golgi retention mechanism and in particular may provide the basis for identification of the DPAP A retention signal receptor. Independent genetic and biochemical approaches will also be pursued that more directly focus on identification of the retention signal receptor. Experiments to determine whether or not retention occurs via retrieval from a post-Golgi compartment will also be performed. The results of these studies should help illuminate the mechanism of yeast Golgi membrane protein retention and add significantly our overall knowledge of membrane protein sorting.