A tyrosine kinase associated with the red cell membrane phosphorylates band 3.

Phosphorylation of Band 3, the anion transport protein of human erythrocyte membranes, has been studied by incubating isolated ghosts with [gamma-32P]ATP. One of the phosphate-acceptor sites is tyrosine 8 in the NH2-terminal cytoplasmic domain of the Band 3 protein. Seven out of 11 residues in the sequence surrounding the phosphorylated tyrosine are Asp or Glu. It is concluded that the erythrocyte, like other cells, contains a membrane-associated tyrosine kinase which phosphorylates highly anionic peptide acceptor sites.