Endoplasmic reticulum resident protein 27, also known as ER protein 27, C12orf46 and ERP27, is an endoplasmic reticulum luminal protein which is a member of the protein disulfide isomerase family. ERP27 contains one thioredoxin domain and does not contain a CXXC active site motif. ERP27 is widely expressed in many tissues; it has highest expression in pancreas, with lower levels in spleen, lung, kidney, thymus, and bone marrow. ERP27 interacts with PDIA3 and binds somatostatin-14 via hydrophobic interactions. ERP27 may act as a protease, protein disulfide isomerase, thiol-disulfide oxidase or phospholipase.