Purification and primary structure of a new bovine spermadhesin

Z13 is a new seminal plasma protein made up of two disulfide-linked 13-kDa subunits that was identified in our laboratory by 2D PAGE. In this report we present the purification of Z13 from bovine seminal plasma. In solution, the protein is a nonglycosylated dimer that presents one interchain disulfide bond and does not show heparin-binding properties. The complete primary structure and the localization of the S-S bridges are reported. The results suggest that Z13 is a new protein of the spermadhesin family whose members are thought to play a prominent role in different aspects of fertilization.