Brain membrane protein band 3 performs the same functions as erythrocyte band 3.

We report the presence of band 3 protein(s) in mammalian brain that performs the same functions as those of erythroid band 3. These functions are anion transport, ankyrin binding, and generation of senescent cell antigen, an aging antigen that terminates the life of cells. Structural similarity of brain and erythroid band 3 is suggested by the reaction of antibodies to synthetic peptides of erythroid band 3 with brain band 3, the inhibition of anion transport by the same inhibitors, and an equal degree of inhibition of brain and erythrocyte anion transport by synthetic peptides of erythroid band 3 (pep-ANION 2, residues 588-602; pep-COOH, residues 812-827; pep-COOH-N6, residues 813-818). One of these segments, pep-COOH, contains antigenic determinants of senescent cell antigen. These findings suggest that the transport domains of erythroid and neural band 3 are similar functionally and structurally and support the hypothesis that the immunological mechanism of maintaining homeostasis is a general physiologic process for removing senescent and damaged cells in mammals and other vertebrates.