Preliminary Evidence for a Regulation of the Plasma Membrane Redox Chain by the Activity of the ATP-Driven H+ Pump in Elodea Densa Leaves
The reduction of extracellular electron acceptors such as Fe (CN) 6 3− by a plasma membrane redox system is associated with the release of H+ into the medium. Recent evidence indicates that the Fe(CN) 6 3− -induced net efflux of H+ depends on an increase in activity of the ATP-driven H+ pump, interpreted as a secundary consequence of the operation of the redox pump. According to this view, the H+ pump would be activated by the depolarization of the transmembrane potential and also by the cytoplasm acidification accompanying Fe (CN) 6 3− reduction by the redox system. On the other hand, fusicoccin, a toxin thought to stimulate the activity of the ATP-driven H+ pump, has been repeatedly reported to increase the rate of Fe(CN) 6 3− reduction.