| Research Abstract |
Recently, a new immunological approach has been used in order to identify highly conserved Golgi components using anti-Golgi human autoimmune antibodies. In these experiments, several new high molecular weight proteins localized in the Golgi complex, i.e. GCP372/giantin (rat homolog GCP364), golgin 245, GCP23O, Golgi antigen p230, p210, GCP17O, GMI3O, golgin 160 and 95. From analysis of complete deduced amino acid sequences of GCP372/giantin, golgin 245, p230, GCP170, GCP112/GM13O and a vesicular transport factor p115, these proteins have common structural elements enabling the formation of coiled-coil analogous to the myosin family. In this report, to get more information of the biological roles of these Golgi associated proteins, we analyzed the targeting mechanism of GCP372/giantin, GCP170, GCP112/GM130 and p115, and characterized its biochemical feature in detail. The Golgi targeting and/or retention signal of giantin is in the C-terminal region of cytoplasmic domain, and transmembrane domain participates partially as a Golgi retention signal. The importance of cytoplasmic domain in giantin for Golgi localization invoking protein-protein interactions rather than interaction between the TMD and lipid bilayer. The phosphorylation -dephosphorylation of GCP 170 and p115 regulates the interaction of these proteins with the Golgi membrane, possibly taking part in the regulatory mechanism of vesicular transport. These localization mechanisms of Golgi resident proteins suggests the protein network surrounding the Golgi apparatus. These protein network including BETA-spectrin and myosin play the role not only in maintaining the Golgi structure but also in vesicular transport to and from the Golgi.
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