Identification of the 2A10 antigen of retinal pigment epithelium as a beta 1 subunit of integrin.

In previous studies the 2A10 antigen of retinal pigment epithelium (RPE) was described. It is a cell-surface monoclonal antibody-defined antigen whose properties suggest a possible role in cell adhesive interactions. This report identified the 2A10 antigen as a beta 1 subunit of the cell-surface extracellular matrix receptor protein, integrin. Comparative biochemical, immunochemical, and histochemical analyses of the 2A10 antibody and other antibodies directed against the beta 1 subunit of integrin indicate similar tissue distributions, immunoblotting patterns, tryptic digestion profiles, and coimmunoprecipitation of the 2A10 antigen and the beta 1 subunit of integrin. The 2A10 antigen/beta 1 subunit differed in molecular weight in different tissues, with the RPE demonstrating a form intermediate between neural and endoderm-derived tissues. The application of this new antibody to functional studies of the role of integrin in RPE cell-substrate adhesion is described in the accompanying paper.