Energized transport of potassium ions in the absence of valinomycin by cytochrome c oxidase-reconstituted vesicles.

Valinomycin-independent energized uptake of K+ was observed in cytochrome c oxidase reconstituted proteoliposome. The rate of K+ influx was proportional to the magnitude of electron flux. The energized uptake of K+ was abolished by p-trifluoromethoxycarbonylcyanide phenylhydrazone or by nigericin. Using the safranine fluorescence technique, it was demonstrated that even in the absence of valinomycin, liposomes and proteoliposomes reconstituted with cytochrome c oxidase are able to discriminate between Na+ and K+ and show a preference for K+ in the presence of excess Na+.