Regulation of glycolysis via reversible enzyme binding to the membrane protein, band 3.

Most metabolic pathways are regulated by feedback inhibition/activation or by covalent modification of a regulatory enzyme. In erythrocytes, however, we demonstrate that glycolysis can be modulated over 30-fold by controlling the availability of glycolytic enzyme binding sites at the extreme N terminus of the anion transporter, band 3. Direct obstruction of these inhibitory sites by anti-peptide Fab's against residues 1-15 of band 3 promotes an approximately 3-fold increase in the rate of lactate production. In contrast, enrichment of the erythrocyte cytoplasm with the band 3 peptide against which the above antibodies were raised results in a more than 10-fold decrease in the rate of lactate accumulation. Control peptides and their derived antipeptide antibodies corresponding to other sequences of band 3 or glycophorin were found to have no effect on lactate production. Analysis of changes in glycolytic intermediates during Fab treatments suggests that hexokinase may be one enzyme that is modulated by association with band 3. We conclude that the extreme N terminus of band 3 can bind and inhibit glycolytic enzymes in vivo and that it probably participates in control of red cell glycolysis.