The identification of a heparin-binding protein on the surface of bovine sperm.

We report the identification of a sperm surface protein which binds tightly to heparin. The protein was isolated by affinity chromatography on heparin agarose, and its affinity for heparin was confirmed by electrophoresis in the presence of heparin under non-denaturing conditions. The protein consists of a single polypeptide chain with a molecular weight of 45,000, as determined by electrophoresis under denaturing conditions. The protein may bind glycosaminoglycans in vivo and play a part in initiating the capacitation/acrosome reaction.