A Monoclonal Antibody Against Erythrocyte Spectrin Reacts with Both Alpha- and Beta-subunits and Detects Spectrin-like Molecules in Non-erythroid Cells

A panel of nine monoclonal antibodies against the characteristic erythrocyte membrane protein spectrin has been isolated. One antibody reacts with both the 240 000 and 220 000 D alpha- and beta-subunits of spectrin after denaturation. The same antibody reacts with a 240 000 D protein present in various hemopoietic and other cell lines, as well as some smaller polypeptides, as established by western blotting and immunoautoradiography. These results indicate that the alpha- and beta-subunits of spectrin, a polypeptide of 240 000, and some smaller polypeptides present in non-erythroid cell types possess a considerable region of sequence homology, but it is not yet clear just how extensively the spectrin-like molecules and other polypeptides are related.