Proacrosin binding protein: immunocomparative studies in boar, bovine, hamster, human and ram

The cross reactivities of acidic extracts from boar, bovine, hamster, human and ram spermatozoa to a polyclonal antibody of the boar proacrosin binding protein has been investigated. The pH 3.0 extracts of the washed spermatozoa from each species were subjected to Western blot analysis using a polyclonal antibody developed against the 28 kDa boar proacrosin binding protein. The boar sperm extracts had a major 28 kD and a minor 29 kDa proacrosin binding protein. A similar protein of 29 kDa was present in the bovine and ram samples, while the hamster had bands at 22 and 25 kDa. Extracts of human sperm yielded a diffuse but distinct area of cross reactivity of about 25-30 kDa. These results demonstrate that proacrosin binding proteins are present in sperm of different mammalian species and they have similar molecular weights.