Protein disulfide isomerase (By similarity). Might play a role in the unfolded protein response (By similarity). May regulate transport of alpha4-beta2 neuronal acetylcholine receptor (By similarity). Catalyzes the rearrangement of -S-S- bonds in proteins. Interacts with CHRNA4 (By similarity). Component of a complex containing at least CRELD2, MANF, MATN3 and PDIA4 (By similarity). Belongs to the CRELD family.