Disulfide reductase. May participate in various redox reactions through the reversible oxidation of its active center dithiol to a disulfide and catalyze dithiol-disulfide exchange reactions. Modulates TNF-alpha signaling and NF-kappa-B activation. Has peroxidase activity and may contribute to the elimination of cellular hydrogen peroxide (By similarity). Interacts with TRXR1 and DYNLL1/DNCL1. The oxidized protein is reduced by TRXR1. Belongs to the thioredoxin family.