Required for fertilization. May be required for cell adhesion and/or function as a signaling molecule. Expressed in spermatids, during spermogenesis expression is primarily localized to the pseudopod. Removing the EGF-like repeats in any combination completely abolishes fertilization. Modifying each EGF repeat by changing a central cysteine residue to a tyrosine disrupts the secondary structure as the specific disulfide bridges responsible for this overall structure are not formed. The cysteine to tyrosine mutation when located in EGF-like domains 1,3,4 and 5, causes a complete loss of function. The same mutation in additional EGF-like domains leads to a temperature sensitive sterile phenotype.