Antibiotic-mediated transport of alkali ions across lipid barriers.

Investigations of the effects of valinomycin on mitochondria" 2 led to the dis- covery of antibiotic-mediated ion transport.3Subsequent work revealed that this property is shared by valinomycin, the enniatins, the macrolide actins, and the gramicidins, including an extensive array of natural and synthetic analogues.4-6Passive ion permeability effects have been reported obtained with these agents on other systems including erythroeytes,7 synthetic lipid vesicles,7 and artificial bi- molecular lipid leaflets.8' 9The macrolide actins can even mediate cation trans-