Elucidation of novel molecular mechanisms in protein transportation from ER to Golgi apparatus and their roles in development

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We previously identified a novel gene misty somites (mys), which encodes Mys protein, and found that almost all vertebrate genomes contain the gene encoding Mys protein homolog. In this study, we newly produced antibodies recognizing carboxy-terminus of human Mys protein, a region highly conserved in vertebrate Mys protein homologs. Mys protein homologs were found to be expressed in human and mouse cultured cells and Xenopus embryos. We then examined the localization of Mys protein in human cultured cells using the newly produced antibody and found that Mys protein was localized in Golgi apparatus and vesicles distributed throughout cytoplasm. We isolated Sec23A protein as a protein interacting with Mys by performing a pull-down assay with Flag-tagged human Mys protein in human cultured cells followed by mass spectrometry analysis. Immunostaining using anti Mys antibody and anti-Sec23A antibody showed co-localization of Mys and Sec23A in Golgi apparatus. Immunoprecipitation using these two antibodies showed the interaction of endogenous Mys and Sec23A. These results suggest that Mys and Sec23A function in Golgi apparatus in cooperation with each other. We are currently performing knock-down experiences and will elucidate roles of Mys in protein transportation.