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Abstract
The Conserved Oligomeric Golgi (COG) complex is a Golgi-localized hetero-octamer consisting of two structurally and functionally distinct subcomplexes: lobe A (Cog1–4) and lobe B (Cog5–8). The complex has been characterized in both yeast and mammals and was proposed to function as a tethering factor for two distinct classes of vesicles: vesicles that recycle within the Golgi apparatus and vesicles that transport from the Endosomes to the Golgi apparatus. Mutations in different COG subunits severely distress the Golgi-glycosylation machinery and result in substantial global alterations in cell surface glycoconjugates. Since the activity of Golgi glycosylation enzymes depends on their proper intra-Golgi localization, the COG complex has been implicated in regulating the trafficking of the Golgi-glycosylation machinery. Consistent with this hypothesis, mutations in different COG subunits have been identified in human genetic diseases known as Congenital Disorders of Glycosylation (CDGs). Despite the extensive studies on COG, the mechanisms by which this complex regulates membrane transport and consequently Golgi-mediated glycosylation are largely unknown. The major goal of my research was to gain molecular insights into the function of the COG complex in mammalian cells.
