Non essential disulfide isomerase, which participates in the folding of proteins containing disulfide bonds. May be involved in glycosylation, prolyl hydroxylation and triglyceride transfer. Able to fold proteins by being directly oxidized by ERO1. Catalyzes the rearrangement of -S-S- bonds in proteins. Present with 1520 molecules/cell in log phase SD medium. Belongs to the protein disulfide isomerase family.