Fig. 4. The biological activity in the peripheral fraction is not due to ZP3 contamination. (A) Wild-type sperm, but not GalT I-null sperm, are inhibited from binding ovulated eggs by a monoclonal antibody against mouse ZP3 (East et al., 1985). Controls were performed with a non-specific rat IgG. Each bar represents the mean±s.d.; n=1 experiment, which was carried out in triplicate. (B) Immunoblot of matrix and peripheral fraction proteins from ovulated zonae pellucidae with a rat monoclonal antibody against mouse ZP3. Molecular weight markers are shown.