Isotypes of protein kinase C in bovine sperm.

Protein kinase C is present in bovine epididymal sperm. The enzyme was partially purified by gel filtration on Sephacryl S-300. The Ca2+/phosphatidylserine-dependent histone phosphotransferase activity elutes from the gel filtration column in a manner corresponding to a Mr approximately 80 kDa. The activity peak also corresponds with 3H]phorbol 12,13-dibutyrate binding activity. Immunoblot analysis of the partially purified enzyme with isozyme-specific monoclonal antibodies revealed the presence of alpha-, beta-, and gamma-subspecies of protein kinase C. Indirect immunofluorescence showed that the antibodies against alpha-, beta-, and gamma-subspecies produced prominent staining of the postacrosomal region of the sperm head. In addition, beta-subspecies antibodies produced minor staining of the midpiece and gamma-subspecies antibodies produced a minor staining of the acrosomal region.