Vacuolar Protein Sorting 33B (VPS33B)

VPS33B is a member of the Sec-1 domain family, and encodes the human ortholog of rat Vps33b which is homologous to the yeast class C Vps33 protein. The mammalian class C Vps proteins are predominantly associated with late endosomes/lysosomes, and like their yeast counterparts, may mediate vesicle trafficking steps in the endosome/lysosome pathway. The deduced 617-amino acid protein has a calculated molecular mass of 70.6 kD. VPS33B shares 96% amino acid identity with rat Vps33b. Homologous proteins were identified in insect, nematode, plant, and yeast databases. Northern blot analysis of 8 tissues detected VPS33B mRNA above the 2.4-kb marker. VPS33B was highly enriched in testis and less abundant in all other tissues.