Résumé
ATP lowers the efficiency of oxidative phosphorylation in Saccharomyces cerevisiae mitochondria by a mechanism that involves the activation of cytochrome c oxidase and the increase in anion permeability of the mitochondrial inner membrane (S. Prieto, F. Bouillaud, and E. Rial (1995) Biochem. J. 307, 657-661). In this study, we have carried out experiments to determine the transport specificity of the ATP-induced permeability pathway and its regulation. The pathway allows permeation of anions such as Cl- or Br- , while NO3-, N02-, or Tes are not transported. Transport is activated by ATP, GTP, dATP, dGTP, and GDP, while ADP, AMP, GMP, and pyrimidine nucleotides are ineffective. Analysis of transport inhibition by ADP and phosphate suggests that ADP is a competitive inhibitor of ATP while phosphate inhibition is noncompetitive. These effectors are operative in the physiological range of concentrations.