Identification of a 70,000-D protein in lens membrane junctional domains

A 70,000-D membrane protein (MP70), which is restricted to the eye lens fibers and is present in immunologically homologous form in many vertebrate species, has been identified. By use of anti-MP70 monoclonal antibodies for immunofluorescence microscopy and electron microscopy, this polypeptide was localized in lens membrane junctional domains. Both immunofluorescence microscopy and SDS PAGE reveal an abundance of MP70 in the lens outer cortex that coincides with a high frequency of fiber gap junctions in the same region.