[Membrane fusion between Ehrlich ascites of mastocarcinoma cells and liposome induced by proton translocation of transplasma membrane NADH-ferricyanide redox enzymes].

By using resonance energy transfer assay (RET) and fluorescence microscopy we show experimental evidence that membrane fusion of Ehrlich ascites of mastocarcinoma cells with liposomes could be induced by the proton translocation activity associated with NADH-ferricyanide redox enzyme of transplasma membrane of cancer cells. The iodoacetate, an inhibitor of glycolysis, was found to be able to depress the proton translocation activity and also to inhibit the membrane fusion. It is suggested that NADH produced mainly by glycolysis is utilized as the substrate (electron donor) for transmembrane ferricyanide reduction, and the proton pumping activity in the cancer cells is coupled to the transmembrane NADH-ferricyanide redox enzyme system. Experiments also show that membrane fusion extent of cancer cells with liposomes is proportional to the amount of H+ pumped out by the cells and membrane fusion process also exhibits a H+ consuming mode just as in fusion process of mitochondria with liposomes by redox enzyme proton pumps of respiratory chain. All of the results presented in this paper consists with recent reports of this laboratory, which indicated that various types of proton pumping system from different membrane system of cell have a new function in membrane fusion. Therefore, the proton pumping induced membrane fusion may have a more general physiological importance in triggering and modulating fusion process of native membrane in vivo.