Radioiodination of surface proteins of bull spermatozoa and their characterization by sodium dodecyl sulphate— polyacrylamide gel electrophoresis

: Surface proteins of ejaculated bull spermatozoa were radioiodinated, solubilized and characterized by sodium dodecyl sulphate--polyacrylamide gel electrophoresis. The electron microscopic autoradiographs showed that the labelling was equally distributed to all parts of the spermatozoon and restricted to the sperm surface. The electrophoresis of solubilized radioactivity revealed 6 radioactive fractions with approximate molecular weights of 67000-69000, 47000-50000, 34000-37000, 25000-28000, and 14000-16000. The 6th fraction probably represented labelled lipids. The electrophoresis of radioiodinated seminal plasma proteins revealed only 2 radioactive protein peaks which coincided with the sperm surface protein fractions IV and V.