Plays a role in acrosome compaction and sperm morphogenesis (PubMed:21911476). Is implicated in sperm-oocyte interaction during fertilization (By similarity). First localized in acrosome granule, later migrates to the inner and outer acrosomal membrane. Released after the acrosomal reaction. Expressed specifically in testis. N-glycosylated. Belongs to the zona pellucida-binding protein Sp38 family.