title: Monomeric erythrocyte band 3 protein transports anions.
abstract: The anion transport system of the human erythrocyte membrane was reconstituted in egg phosphatidylcholine membranes by using either the unmodified transport protein, band 3, or covalently crosslinked band 3 dimers. Unilamellar vesicles of a diameter of 32 +/- 3 nm were then isolated from the sample by passage through a French press and subsequent gel filtration. According to sedimentation equilibrium measurements, around 85% of the vesicles were devoid of protein. The remaining 15% contained either a single band 3 monomer or, when crosslinked band 3 protein was used, a single band 3 dimer. Vesicles containing either single monomers or single dimers showed a rapid, inhibitor-sensitive sulfate efflux, and the turnover numbers of band 3 for the inhibitor-sensitive flux component were identical in both systems. This shows that monomeric band 3 protein is able to transport anions and that dimerization of the protein does not change its transport activity.
authors.affiliation: Max-Planck-Institute of Biophysics, Johann Wolfgang Goethe University, Frankfurt am Main, Federal Republic of Germany.
authors.forename: S
authors.initials: S
authors.lastname: Lindenthal
authors.forename: D
authors.initials: D
authors.lastname: Schubert
mesh_terms: D001457:Anion Exchange Protein 1, Erythrocyte / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D001692:Biological Transport; D004910:Erythrocyte Membrane / Q000378:metabolism; D006801:Humans; D046911:Macromolecular Substances; D008433:Mathematics; D008962:Models, Theoretical; D011487:Protein Conformation; D013431:Sulfates / Q000097:blood
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D046911:Macromolecular Substances; D013431:Sulfates