Equilibrium ligand binding to the human erythrocyte sugar transporter. Evidence for two sugar-binding sites per carrier.

摘要: Equilibrium [3H]cytochalasin B binding to class I sites of human red cell membranes (the sugar transporter) was examined in the presence and absence intracellular or extracellular sugars known interact with transport system. D-Glucose, a transported sugar, is without effect on cytochalasin when present medium but an effective inhibitor within cell. Ethylidene glucose maltose (reactive nontransported sugars) inhibit (CCB) either outside inside Inhibition by (Si) simple, linear competitive type. (So) more complex; Kd(app) for increases saturable fashion [So]. These observations are compared predictions one-site, alternating conformer model two-site substrate transporter, X. The experimental results inconsistent one-site explained which ternary complexes So . X Si CCBi exist where display negative cooperativity occupied little no species, D-glucose.