The K+ channel KIR2.1 functions in tandem with proton influx to mediate sour taste transduction

Among the five basic tastes, sour is one of the least understood. Notably, the sour receptor remains to be identified, and molecular mechanisms by which sour stimuli are detected are largely not known. Previous work has shown that H⁺ ions can directly enter sour taste cells, eliciting a change in membrane potential and acidification of the cell cytosol. In the present work, we identify a second element of sensory transduction, a K⁺ channel, K_IR2.1, which is inhibited by intracellular acidification. The presence of an acid-sensitive K⁺ channel in sour taste cells allows for amplification of the sensory response and may explain why weak acids that produce intracellular acidification, such as acetic acid, taste more sour than strong acids.