Could enhance the fertilizing capacity of spermatozoa upon interaction with heparin-like glycosaminoglycans present in the female genital tract. One glycoform exists as a monomer while the other forms a heterotetramer with HSP-2 and binds heparin. Major component of seminal plasma. O-glycosylated on Thr. There are two forms of HSP-1 which probably differ in the amount of sialylation of polysaccharide. Belongs to the seminal plasma protein family.