[Changes in protein phosphorylation during acrosome reaction of mouse sperm]

The changes of protein phosphorylation were analyzed during mouse sperm capacitation and acrosome reaction. Sperm adenosine 3',5'-cyclic monophosphate (cAMP) levels were gradually elevated during capacitation period. Although 32P uptake by sperm and protein phosphorylation increased during capacitation, the phosphorylation of a 45-kDa protein remained to be relatively constant. It was also demonstrated that acrosome reaction was induced by the treatment of capacitated sperm with 0.1 mM dibutyryl cAMP, 10 mM dibutyrylguanosine 3',5'-cyclic monophosphate, 20 microM calcium ionophore A23187 or acid-solubilized zonae pellucidae. The phosphorylation of a 45-kDa protein was augmented during the acrosome reaction induced by such agents. These results suggest that changes in protein phosphorylation might be involved in the regulation of mouse sperm capacitation and acrosome reaction.