Just as calcium plays an integral role in acrosome capacitation and reaction, several spermatozoon proteins have been reported as binding to the ovum at fertilization. We examined the relationship between thawed bovine semen protein profiles, seminal plasma calcium ion concentration, spermatozoon phospholipase A2 (PLA2) activity and acrosome reaction. Electrophoretic profile analysis of spermatozoa and bovine seminal plasma proteins (total and membrane) revealed qualitative and quantitative differences among bulls. Variations in PLA2 and seminal plasma calcium concentration indicated genetic diversity among individuals. A 15.7-kDa membrane protein was significantly correlated (r = 0.71) with acrosome reaction, which in turn has been associated with in vivo fertility.
