Duplication of genes encoding non-clathrin coat protein γ-COP in vertebrate, insect and plant evolution.

Abstract Coatomer is a major component of COPI vesicles and consists of seven subunits. The γ-COP subunit of the coatomer is believed to mediate the binding to the cytoplasmic dilysine motifs of membrane proteins. We characterized cDNAs for Copg genes encoding γ-COP from mouse, zebrafish, Drosophila melanogaster and Bombyx mori . Two copies of Copg genes are present in vertebrates and in B. mori . Phylogenetic analysis revealed that two paralogous genes had been derived from a single ancestral gene by duplication independently in vertebrates and in B. mori . Mouse Copg1 showed ubiquitous expression with the highest level in testis. Zebrafish copg2 was biallelically expressed in hybrid larvae in contrast to its mammalian ortholog expressed in a parent-of-origin-specific manner. A phylogenetic analysis with partial plant cDNA sequences suggested that copg gene was also duplicated in the grass family (Poaceae).