Vacuolar sorting proteins (VPSs) are required for proper trafficking of endocytic and biosynthetic proteins to the vacuole and play an important role in the budding process of cells. VPS35 (vacuolar protein sorting 35), also known as MEM3, is the 796 amino acid human homolog of the S. cerevisiae Vps35 protein. Localized to the cytoplasm and to the peripheral membrane, VPS35 is an essential component of the retromer complex which is involved in retrieval of lysosomal enzyme receptors from endosomes to the trans-Golgi network. VPS35 is expressed ubiquitously with highest expression in heart, placenta, brain, testis, kidney, colon, ovary and spleen. In addition to its crucial role in the retromer complex, VPS35 is part of a subcomplex that is required to regulate transcytosis of the polymeric immunoglobulin receptor from the basolateral to the apical surface of epithelial cells and hepatocytes.
