Endoplasmic Reticulum Resident Protein 57 (ERp57)

The PDIA3 protein has protein disulfide isomerase activity. PDIA3 is also part of the major histocompatibility complex (MHC) class I peptide-loading complex (TAP1), which is essential for formation of the final antigen conformation and export from the endoplasmic reticulum to the cell surface.

The cDNA encoding human GRP58 was cloned independently by Bourdi et al. (1995), Koivunen et al. (1996), and Hirano et al. (1995). All reported that the gene encodes a 505-amino acid polypeptide with significant homology to human protein disulfide isomerase (PDI). Bourdi et al. (1995) noted that the sequence includes a putative nuclear localization motif and an endoplasmic reticulum (ER)-retention/retrieval motif.