FERTILIZATION ANTIGEN (FA-1) COMPLETELY BLOCKS HUMAN SPERM BINDING TOHUMAN ZONA-PELLUCIDA - FA-1 ANTIGEN MAY BE A SPERM RECEPTOR FOR ZONA-PELLUCIDA IN HUMANS

The effects of purified human sperm fertilization antigen-1 (FA-1), af finity-purified monoclonal Fab' antibody to FA-1, and monoclonal Fab' antibody to phosphotyrosine residues on human sperm-zona interaction w ere investigated. The purified FA-1 antigen completely blocked sperm b inding to zona pellucida (P < 0.0001). Also, the monoclonal Fab' antib odies to FA-1 antigen and phosphotyrosine residues significantly (P < 0.05) reduced sperm-zona pellucida interaction. Effects were observed when FA-1 antigen was preincubated with zonae pellucidae and the antib odies were preincubated with sperm before insemination and not vice ve rsa. These results suggest that the tyrosine phosphorylation especiall y of FA-1 antigen has an important role in zona pellucida receptor rec ognition and binding. These findings also suggest that FA-1 antigen ma y be the sperm receptor involved in zona pellucida binding in humans.