Probable disulfide isomerase, which participates in the folding of proteins containing disulfide bonds. May act as a dithiol oxidase. Catalyzes the rearrangement of -S-S- bonds in proteins. E(0) is -157 mV. Widely expressed. Expressed in brain, testis, lung, skin, kidney, uterus, bone, stomach, liver, prostate, placenta, eye and muscle. Not up-regulated by unfolded protein response (UPR). The di-lysine motif confers endoplasmic reticulum localization for type I membrane proteins. N-glycosylated. Belongs to the protein disulfide isomerase family. Extended N-terminus. Extended N-terminus.