Anti-ARP antibodies enable researchers to detect and measure the ARP antigen in biological samples. This target is a reported synonym of the CRISP1 gene, which encodes cysteine rich secretory protein 1. This protein is suspected to have a role in sperm-egg fusion and maturation. The human version of ARP has a canonical amino acid length of 249 residues and a protein mass of 28.5 kilodaltons, although 2 isoforms have been identified. It is reported to be localized in the mitochondria of cells and notably expressed in the epididymis. ARP is a member of the CRISP protein family.