Immunological detection of an analogue of the erythroid protein 4.1 in endothelial cells.

Endothelial cells (EC) of arterial and venous origin were investigated by indirect immunofluorescence and immunoautoradiography for the presence of red cell membrane 4.1-like protein. By immunofluorescence, EC exhibited a relatively uniform fluorescent staining sometimes of a reticular pattern, distributed over the entire cell. All controls were negative. Immunoblot analysis of EC revealed a cross reactive band of a molecular weight comparable to that of the erythrocyte band 4.1. These findings indicate that endothelial cells of arterial and venous origin express a polypeptide immunologically related to the erythrocyte protein 4.1, which may play an important role in membrane-cytoskeleton interactions.