Calcium-binding protein that interacts with newly synthesized monoglucosylated glycoproteins in the endoplasmic reticulum. It may act in assisting protein assembly and/or in the retention within the ER of unassembled protein subunits. It seems to play a major role in the quality control apparatus of the ER by the retention of incorrectly folded proteins. Required for embryogenesis and larval development under heat and ER stress conditions. May be important for germ cell development. Involved in neuronal necrotic cell death (By similarity). Glycosylation is important for its biological activity. Belongs to the calreticulin family.