SEC22 Vesicle Trafficking Protein Homolog A (SEC22A)

The S. cerevisiae Sec22, Bet1, and Bos1 genes encode interacting proteins that play a role in endoplasmic reticulum (ER)-Golgi transport. Using human brain cDNA sequences homologous to yeast Sec22 and Bet1 to screen a rat liver cDNA library, Hay et al. (1996) cloned rat homologs of both yeast genes. The rat SEC22 cDNA, later designated SEC22A, encodes a deduced 254-amino acid integral membrane protein with a predicted molecular mass of 28.5 kD and a transmembrane domain at or near the C terminus. The rat and yeast proteins share 32% overall sequence identity. Northern blot analysis detected a 2.6-kb transcript in all 7 rat tissues tested, with predominant expression in lung and liver. Immunofluorescence microscopy of epitope-tagged SEC22A in transfected COS cells demonstrated localization in the endoplasmic reticulum.