Functions during spermatogenesis as a chaperone for a range of client proteins that are important for sperm adhesion onto the egg zona pellucida and for subsequent penetration of the zona pellucida. Required for normal sperm migration from the uterus into the oviduct. Required for normal male fertility. Binds calcium ions. Interacts with PDILT and PPIB (By similarity). Interacts with ADAM2. Interacts with ADAM1A, ADAM1B and ADAM3; these are protein-coding genes in mouse but may be pseudogenes in other organisms. Detected in testis (at protein level). Detected in testis. Specifically expressed during male meiotic germ cell development. First detected in early pachytene spermatocytes. Expression is highest in elongating and round spermatids and decreases thereafter. Not detectable in mature spermatids. Male mice show normal mating behavior and produce morphologically normal sperm, but are nearly sterile. Mutant sperm fail to adhere to the egg zona pellucida and are generally unable to penetrate the egg extracellular matrix. In addition, mutant sperm display defects in migration from the uterus into the oviduct. Belongs to the calreticulin family.