Does not seem to be a disulfide isomerase. Plays an important role in the processing of secretory proteins within the ER (By similarity). Homodimer. Part of a large chaperone multiprotein complex comprising DNAJB11, HSP90B1, HSPA5, HYOU, PDIA2, PDIA4, PDIA6, PPIB, SDF2L1, UGGT1 and very small amounts of ERP29, but not, or at very low levels, CALR nor CANX (By similarity).