Low P S, Rathinavelu P, Harrison M L
Department of Chemistry, Purdue University, West Lafayette, Indiana 47907.
J Biol Chem. 1993 Jul 15;268(20):14627-31.
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.
大多数代谢途径是通过反馈抑制/激活或对调节酶的共价修饰来调控的。然而，在红细胞中，我们证明糖酵解可通过控制阴离子转运蛋白带3极端N端的糖酵解酶结合位点的可用性而被调节30倍以上。针对带3第1-15位残基的抗肽Fab直接阻断这些抑制位点可使乳酸生成速率提高约3倍。相反，用上述抗体所针对的带3肽富集红细胞细胞质会导致乳酸积累速率下降10倍以上。发现对应于带3或血型糖蛋白其他序列的对照肽及其衍生的抗肽抗体对乳酸生成没有影响。对Fab处理过程中糖酵解中间产物变化的分析表明，己糖激酶可能是一种通过与带3结合而被调节的酶。我们得出结论，带3的极端N端在体内可结合并抑制糖酵解酶，并且它可能参与红细胞糖酵解的调控。
