The Golgi apparatus is a central station for protein trafficking in eukaryotic cells. A widely accepted model of protein transport within the Golgi apparatus is cisternal maturation. Each cisterna has specific resident proteins, which are thought to be maintained by COPI-mediated transport. However, the mechanisms underlying specific sorting of these Golgi-resident proteins remain elusive. To obtain a clue to understand the selective sorting of vesicles between the Golgi cisterenae, we investigated the molecular arrangements of the conserved oligomeric Golgi (COG) subunits in yeast cells. Mutations in COG subunits cause defects in Golgi trafficking and glycosylation of proteins and are causative of Congenital Disorders of Glycosylation (CDG) in humans. Interactions among COG subunits in cytosolic and membrane fractions were investigated by co-immunoprecipitation. Cytosolic COG subunits existed as octamers, whereas membrane-associated COG subunits formed a variety of subcomplexes. Relocation of individual COG subunits to mitochondria resulted in recruitment of only a limited number of other COG subunits to mitochondria. These results indicate that COG proteins function in the forms of a variety of subcomplexes and suggest that the COG complex does not comprise stable tethering without other interactors.Key words: The Golgi apparatus, COG complex, yeast, membrane trafficking, multi-subunit tethering complex.

中文翻译：

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酵母 COG 复合物相互作用的详细分析。

高尔基体是真核细胞中蛋白质运输的中心站。高尔基体中被广泛接受的蛋白质转运模型是脑池成熟。每个池都有特定的常驻蛋白，被认为是由 COPI 介导的运输维持的。然而，这些高尔基体蛋白的特定分类机制仍然难以捉摸。为了获得了解高尔基体之间囊泡选择性分选的线索，我们研究了酵母细胞中保守的寡聚高尔基体 (COG) 亚基的分子排列。COG 亚基的突变会导致高尔基体运输和蛋白质糖基化的缺陷，并且是人类先天性糖基化障碍 (CDG) 的原因。通过免疫共沉淀研究细胞质和膜组分中 COG 亚基之间的相互作用。胞质 COG 亚基以八聚体形式存在，而膜相关 COG 亚基形成多种亚复合体。将单个 COG 亚基重新定位到线粒体导致仅将有限数量的其他 COG 亚基募集到线粒体。这些结果表明 COG 蛋白以多种亚复合物的形式发挥作用，并表明 COG 复合物在没有其他相互作用物的情况下不包含稳定的束缚。 关键词：高尔基体，COG 复合物，酵母，膜运输，多亚基束缚复合物. 将单个 COG 亚基重新定位到线粒体导致仅将有限数量的其他 COG 亚基募集到线粒体。这些结果表明 COG 蛋白以多种亚复合物的形式发挥作用，并表明 COG 复合物在没有其他相互作用物的情况下不包含稳定的束缚。 关键词：高尔基体，COG 复合物，酵母，膜运输，多亚基束缚复合物. 将单个 COG 亚基重新定位到线粒体导致仅将有限数量的其他 COG 亚基募集到线粒体。这些结果表明 COG 蛋白以多种亚复合物的形式发挥作用，并表明 COG 复合物在没有其他相互作用物的情况下不包含稳定的束缚。 关键词：高尔基体，COG 复合物，酵母，膜运输，多亚基束缚复合物.