High molecular weight microtubule‐associated proteins from pig brain are immunologically related to human erythrocyte membrane proteins spectrin, ankyrin, proteins 4.1 and 4.2

The microtubule‐associated proteins MAPs 1 and 2 from pig brain have been found to react with antibodies directed against human ankyrin and spectrin, respectively (Bennett and Davis, 1981; Davis and Bennett, 1982). In a complementary approach we have prepared antibodies against MAP1 alpha. MAP1 gamma and MAP2 purified from pig brain and tested their reactivity with human erythrocyte membrane proteins. Anti‐MAP1 alpha was shown to react with alpha and beta‐spectrin and with protein 4.1; anti‐MAP1 gamma reacted with alpha‐spectrin and ankyrin and with a 60 K peptide which copurified with human spectrin. Finally anti‐MAP2 was specific for beta‐spectrin and protein 4.2. The biological function of protein 4.2 is still unknown but details on the interactions between ankyrin, spectrin and protein 4.1 and their role in mediating the linkage of oligomeric actin on the erythrocyte membrane are well documented. The present results, which demonstrate extended immunological analogies between pig brain high molecular weight MAPs and human erythrocyte membrane proteins, may reflect the presence, in the two families of proteins, of similar functionally important epitopes.