Inhibition of motility of hamster spermatozoa by protein tyrosine kinase inhibitors

Genistein, tyrphostin and piceatannol, which are specific inhibitors of pro tein tyrosine kinase, were screened for their effects on the motility of in tact and demembranated hamster spermatozoa. Of the three inhibitors only pi ceatannol inhibited the motility of intact spermatozoa. None of the inhibit ors had any inhibitory effect on the reactivation of motility of demembrana ted hamster spermatozoa. Taken together these results indicated that a prot ein tyrosine kinase associated with the membrane of hamster spermatozoa was probably involved in sustenance of hamster sperm motility. Therefore in th e present study a membrane-associated protein tyrosine kinase was purified from a detergent-soluble extract of plasma membranes of mature hamster sper matozoa. The purification involved cation exchange chromatography on fast p rotein liquid chromatography (FPLC) followed by affinity chromatography eit her on an antiphosphotyrosine antibody agarose or poly glu-tyr agarose colu mn. The pure protein tyrosine kinase had an apparent molecular mass of 45 k Da. The enzyme was not inhibited by genistein or herbimycin but was inhibit ed by piceatannol. This is the first report on the purification of a sperm plasma membrane-associated protein tyrosine kinase, an enzyme which has als o been implicated in hamster sperm motility.