Solubilization of four porcine zona pellucida antigens by lithium 3,5-diiodosalicylate.

The lack of detailed studies of zona pellucida antigens up to the present time is partly due to the difficulty of the purification procedures involved. In the present work 4 porcine zona pellucida antigens were isolated using lithium 3,5-diiodosalicylate as the solubilizing agent, and immuno-affinity chromatography, with immobilized IgG, for purification. This method is believed to be more specific than the previous techniques used. The four zona antigens. ZPI/1 (Mr = 42000), ZPII/1 (Mr = 67000), ZPII/2 Mr=32000), and ZPIII/1 (Mr = 17000), were identified. Based on the reaction of the antigens with antibodies induced by intact and heat-solubilized zonae, it is postulated that only ZPI/1 and ZPII/1 are expressed on the surfaces of intact zonae. The cross reaction between human and porcine zona pellucida antigens is attributed to ZPI/1.