The complex of band 3 protein of the human erythrocyte membrane and glyceraldehyde-3-phosphate dehydrogenase: stoichiometry and competition by aldolase.
The cytoplasmic domain of band 3, the main intrinsic protein of the erythrocyte membrane, possesses binding sites for a variety of other proteins of the membrane and the cytoplasm, including the glycolytic enzymes glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and aldolase. We have studied the stoichiometry of the complexes of human band 3 protein and GAPDH and the competition by aldolase for the binding sites. In addition, we have tried to verify the existence of mixed band 3/GAPDH/aldolase complexes, which could represent the nucleus of a putative glycolytic multienzyme complex on the erythrocyte membrane. The technique applied was analytical ultracentrifugation, in particular sedimentation equilibrium analysis, on mixtures of detergent-solubilized band 3 and dye-labelled GAPDH, in part of the experiments supplemented by aldolase. The results obtained were analogous to those reported for the binding of hemoglobin, aldolase and band 4.1 to band 3: (1) the predominant or even sole band 3 oligomer forming the binding site is the tetramer. (2) The band 3 tetramer can bind up to four tetramers of GAPDH. (3) The band 3/GAPDH complexes are unstable. (4) Artificially stabilized band 3 dimers also represent GAPDH binding sites. In addition it was found that aldolase competes with GAPDH for binding to the band 3 tetramer, and that ternary complexes of band 3 tetramers, GAPDH and aldolase do exist.
von Rückmann
Bogdan
B
Institut fur Biophysik, J.W. Goethe-Universitat, Theodor-Stern-Kai 7, Haus 74, D-60590 Frankfurt am Main, Germany.
Schubert
Dieter
D
D001457:Anion Exchange Protein 1, Erythrocyte / Q000737:chemistry*; D001665:Binding Sites; D001667:Binding, Competitive; D019281:Dimerization; D004910:Erythrocyte Membrane / Q000201:enzymology*; D016650:Fluorescein-5-isothiocyanate / Q000737:chemistry; D005634:Fructose-Bisphosphate Aldolase / Q000737:chemistry*; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000737:chemistry*; D006801:Humans
D001457:Anion Exchange Protein 1, Erythrocyte; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D005634:Fructose-Bisphosphate Aldolase; D016650:Fluorescein-5-isothiocyanate