title: The state of association of band 3 protein of the human erythrocyte membrane in solutions of nonionic detergents.
abstract: Band 3 protein, the anion transport protein of the human erythrocyte membrane, was solubilized and purified in aqueous solutions of two nonionic detergents: Ammonyx-LO (dimethyl laurylamine oxide) and C12E9 (nonaethylene glycol lauryl ether). The state of association of the purified protein was studied by analytical ultracentrifugation. Band 3 protein solubilized and studied in solutions of Ammonyx-LO was found to be in a monomer/dimer/tetramer association equilibrium. Band 3 protein freshly prepared in C12 E9 showed the same behaviour; however, during aging the protein was converted into stable noncovalent dimers. The conversion was retarded by the presence of beta-mercaptoethanol or by treatment of the samples with iodoacetamide; it seems to be due to oxidation of the protein by degradation products of the detergent. It is concluded that a monomer/dimer/tetramer association equilibrium is the native state of association of band 3 protein solubilized by nonionic detergents. Since nonionic detergents are assumed not to interfere with protein-protein interactions among membrane proteins, the results strongly support the claim that, in the erythrocyte membrane, band 3 is in a monomer/dimer/tetramer association equilibrium (Dorst, H.-J. and Schubert, D. (1979) Hoppe-Seyler's Z. Physiol. Chem. 360, 1605-1618).
mesh_terms: D001457:Anion Exchange Protein 1, Erythrocyte; D001798:Blood Proteins / Q000032:analysis*; D004123:Dimethylamines; D004591:Electrophoresis, Polyacrylamide Gel; D004910:Erythrocyte Membrane / Q000032:analysis*; D004912:Erythrocytes / Q000032:analysis*; D006801:Humans; D046911:Macromolecular Substances; D008970:Molecular Weight; D000077423:Polidocanol; D011092:Polyethylene Glycols; D012996:Solutions
chemical_list: D001457:Anion Exchange Protein 1, Erythrocyte; D001798:Blood Proteins; D004123:Dimethylamines; D046911:Macromolecular Substances; D012996:Solutions; D000077423:Polidocanol; D011092:Polyethylene Glycols; C014518:dodecyldimethylamine oxide