The perinuclear theca 32 (PT32) protein is disclosed and shown to interact with tyrosine kinase c-Yes. PT32, c-Yes, fragments thereof, and molecules that bind thereto can be used in methods of enhancing fertility, treating or diagnosing diminished fertility and abnormal spermiogenesis, in providing contraception, and in identifying contraceptive and fertility-enhancing agents. Transgenic, non-human animals also are disclosed.