Activation of the potassium uptake system during fermentation in Saccharomyces cerevisiae

Fermentable sugars activated the K+ uptake system, increasing the Vmaxs of Rb+, Na+, and Li+ influxes, but sugars did not affect the effluxes of these cations. This activation seems to be a direct effect of fermentation and not the consequence of the H+ pump ATPase activation or internal pH decrease produced by fermentation.