Probable asymmetry in the organization of components of the hamster zona pellucida.

The distribution of the sperm-, lectin- and antibody-binding components was examined on isolated fragments of the hamster zona pellucida. In all three studies, binding was much stronger on the outer than on the inner surface of the zona pellucida. Fab antibody-binding sites were different from those for various lectins since there appeared to be no competition for binding. Multiple components are obviously exposed on the surfaces of the zona pellucida because the sperm receptor sites are also inaccessible to Fab fragments. We conclude that although the components may be present throughout the zona they are asymmetrically arranged in relation to both surfaces. Microdisc PAGE of zonae from ovulated eggs revealed three major components of molecular weight 240 000, 150 000 and 80 000. These are probably glycoproteins and thus resemble the glycoprotein composition of the mouse zona.