May play a role in acrosome formation in spermatogenesis and in fertilization. Exclusively localized on a peripheral part of acrosome membrane (Golgi phase), localized on the equatorial segment of the acrosome (maturation phase). Present at high level in testis (at protein level). Increased in an age-dependent manner from postnatal 3 to 8 weeks. Males are infertile, due to severe defect of disrupting acrosome formation. Truncated N-terminus. Truncated C-terminus.