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 (PubMed:16238698). Catalyzes the rearrangement of -S-S- bonds in proteins. Interacts with CHRNA4 (PubMed:16238698). Component of a complex containing at least CRELD2, MANF, MATN3 and PDIA4 (By similarity). Ubiquitously expressed (PubMed:16238698). Highly expressed in skeletal muscle, heart, liver, kidney and placenta (PubMed:16238698). Expressed in all fetal tissues tested. Minor isoform. Belongs to the CRELD family.