ENERGIZATION OF YEAST PLASMALEMMA IS REQUIRED FOR ACTIVATION OF ITS H-ATPASE BY GLUCOSE()

Plasmalemma H+-ATPase of Saccharomyces, Schizosaccharomyces, and Candi da yeast cells or protoplasts is known to be activated upon incubation with glucose. We found that preincubation of cells with 2-mercaptoeth anol 2,4-dinitrophenol, gramicidin D, nigericin, or monensin drastical ly decreases the extent of H+-ATPase activation by glucose. The last t wo ionophores abolished activation completely. These effects are expla ined by the deenergization of yeast plasmalemma on incubation with the ionophores or 2-mercaptoethanol, the latter also acting as an uncoupl er. Thus, glucose activates H+-ATPase only in energized yeast plasmale mma.