Plasma membrane H+-ATPase of Saccharomyces cerevisiae is ac-tivated by D-glucose. We found that in the absence of glucose, this enzyme forms a complex with acetylated tubulin. When cells were treated with glucose, the H+-ATPase/tubulin complex was dissoci-ated increasing the enzyme activity with concomitant decrease of acetylated tubulin in plasma membrane. The effect of glucose is inhibited by 2-deoxy-D-glucose, a competitive inhibitor of glucose uptake. Whereas total tubulin is distributed uniformly throughout the cell, acetylated tubulin is concentrated near the plasma membrane. Results from immunoprecipitation experiments indicated physical interaction between acetylated tubulin and H+-ATPase which was disrupted by treatment with 1 mM glucose. Double immunofluorescence observed by confocal microscopy indicated that H+-ATPase and acetylated tubulin partially co-localize at the periphery of glucose-starved cells, with predominance at the outer and inner side of the membrane, respectively. Co-localization was not observed when cells were pretreated with 1 mM glucose. Biochemical experiments using isolated membranes from yeast and purified tubulin from rat brain demonstrated inhibition of H+-ATPase activity by acetylated tubulin, and concomitant increase of H+-ATPase/tubulin complex.
