title: Band 3 tyrosine kinase. Association with the human erythrocyte membrane.
abstract: Band 3, the anion transport protein of the human erythrocyte membrane, is known to be phosphorylated in ghosts at tyrosine 8. The band 3 tyrosine kinase is now shown to be associated with the Triton X-100 insoluble membrane skeleton but not with spectrin or actin. The kinase was reversibly dissociated from membranes and skeletons at elevated ionic strength (50% at mu = 0.15). The binding capacity of the membranes exceeded their native complement of the kinase by at least 60-fold. Prior removal of all peripheral proteins from the cytoplasmic surface of inside-out vesicles did not diminish the rebinding of the kinase, whereas prior removal of band 3 and other accessory proteins from skeletons abolished the rebinding of the kinase. An excess of glyceraldehyde-3-P dehydrogenase, which binds to band 3 in the region of the phosphate acceptor tyrosine 8, both inhibited the phosphorylation of band 3 and released the kinase into solution. Soluble 40/45-kDa chymotryptic fragments from the cytoplasmic pole of band 3 were phosphorylated at least as well as membranous band 3 and caused the release of the kinase from Triton-extracted skeletons. Membrane skeletons lacked most of the membrane band 3, but retained most of the kinase. Nevertheless, the band 3 population solubilized by Triton X-100 from prelabeled ghosts was as well phosphorylated as the population of band 3 retained by the skeletons. Furthermore, the fraction of band 3 not associated with the skeletons following Triton X-100 extraction was a good substrate for the solubilized kinase. We conclude that this tyrosine kinase is reversibly bound to the membrane through electrostatic interactions with the polyacidic sequence surrounding the phosphate accepting tyrosine 8 on band 3. The kinase appears to be preferentially linked to those band 3 molecules associated with the membrane skeleton, but it impartially phosphorylates band 3 species free in the bilayer as well as band 3 fragments in solution. The resemblance of its plasma membrane binding behavior to that of tyrosine kinases of certain viruses causing oncogenic transformation is discussed.
mesh_terms: D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism*; D001665:Binding Sites; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000032:analysis*; D006801:Humans; D008970:Molecular Weight; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000097:blood*; D012995:Solubility; D013379:Substrate Specificity
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D011505:Protein-Tyrosine Kinases