An arginine/histidine exchange transport system in vacuolar-membrane vesicles of Saccharomyces cerevisiae

Abstract

High-affinity arginine-uptake activity in vacuolar-membrane vesicles from the yeast Saccharomyces cerevisiae was detected in the presence of ATP and histidine. Histidine increased the initial rate of uptake and the steady level of accumulation of arginine. When the vesicles were preloaded with histidine in the absence of ATP and diluted, transient uptake of arginine took place with concomitant downhill efflux of histidine from the vesicles. Kinetic examination indicated the existence of a unique transport system which catalyzed exchange of 1 mol of arginine outside with 1 mol of histidine inside the vacuolar membrane. The Ktentry for arginine and the Ktexit for histidine were determined to be 0.1 and 1.1 mM, respectively.