ATP OPENS AN ELECTROPHORETIC POTASSIUM-TRANSPORT PATHWAY IN RESPIRINGYEAST MITOCHONDRIA

In the presence of KCl and only at low phosphate concentrations, ATP s timulated state 4 of the respiration of isolated yeast mitochondria, T his effect could be related to a partial collapse of the transmembrane potential which was created by the respiratory chain or the F0F1-ATPa se. Sodium and lithium could not replace potassium ion. Atractyloside prevented the opening of this K+ pathway, suggesting that only matrici al ATP operated. All these effects were inhibited by increasing phosph ate concentration, or by adding propranolol, quinine, Zn2+ or Mg2+.