Cell membranes from the human lens contain two major polypeptides with molecular weights near 26,000 and 22,000. These two species have been isolated in a highly purified state and purified by means of an antiserum against the 26,000 dalton membrane polypeptide from bovine lens. Immunochemical data are presented that establish a clear structural relationship between the two polypeptides and are consistent with the hypothesis that the 22,000 dalton species derived proteolytically from the 26,000 dalton species.