Endoplasmic reticulum disulfide reductase involved both in the correct folding of proteins and degradation of misfolded proteins. Required for efficient folding of proteins in the endoplasmic reticulum by catalyzing the removal of non-native disulfide bonds formed during the folding of proteins, such as LDLR. Also involved in endoplasmic reticulum-associated degradation (ERAD) by reducing incorrect disulfide bonds in misfolded glycoproteins recognized by EDEM1. Interaction with HSPA5 is required its activity, not for the disulfide reductase activity, but to facilitate the release of DNAJC10 from its substrate. Promotes apoptotic signaling pathway in response to endoplasmic reticulum stress. Interacts with EDEM1 (By similarity). Interacts with HSPA5 (via its J domain). By endoplasmic reticulum stress. The thioredoxin-like regions Trxb 1 and 2 lack a redox-active CXXC motif. Thioredoxin domains 3 and 4 are the primary reductase domains. Truncated N-terminus. Truncated N-terminus.