Effect of tribenzylphosphate on the active phosphate transport and ATP synthesis in yeast mitochondria

Tribenzylphosphate (TBP), a specific inhibitor of the high affinity system for Pi transport in yeast mitochondria, inhibits the active Pi transport measured by the energy-linked swelling. The depence of the rate of oligomycin sensitive ATP synthesis as a function of the external Pi concentration shows two kinetic systems. The high affinity system, corresponds to the range of the external Pi concentration which stimulates the respiratory rate. TBP inhibits both this system and the state 4 → state 3 transition.