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 (By similarity). 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. Perinuclear localization in excretory and germ cells. In intestinal cells, clustered signals around vacuoles with vesicles are detected. Expressed ubiquitously in every blastomere of the embryo up to the gastrulation stage. Expression becomes gradually restricted to the head and tail regions at the comma stage during embryogenesis. During postembryonic development, expressed prominently in the H-shaped excretory cell, in the neurons of head (including ASK and ADL) and tail (including PHA and PHB), in the dorsal and ventral nerve cords, and in the spermatheca. Expressed in the spicules of the male tail (at protein level). Expressed both maternally and zygotically. By stress conditions, such as higher temperature, EGTA, DTT or tunicamycin (at protein level). Glycosylation is important for its biological activity. Reduced fertility and slowed development. Temperature-sensitive reproduction defects. Belongs to the calreticulin family.