Human spermatozoal FA-1 binds with ZP3 of porcine zona pellucida

Experiments were carried out to study the binding of the major porcine zona pellucida glycoprotein ZP3 (Mr = 55,000) with human FA-1, a fertilization-related antigen isolated from human male germ cell plasma membranes and with GA-1, a germ cell antigen isolated from murine male germ cell plasma membranes. FA-1 showed a dose-dependent binding with ZP3 in an enzyme-linked immunosorbent assay (ELISA) and by the Western blot procedure. FA-1 also bioneutralized the sperm ligand activity of ZP3 in a boar sperm/porcine zona pellucida attachment assay. In contrast, GA-1 displayed no reactivity for ZP3 using any of these procedures. These results indicate that FA-1 but not GA-1 has zona pellucida binding activity in the porcine system.