The mechanism that “turns on” taste cells (i.e. the lightning quick chain of events in which our brains process and respond to the foods we put on our tongues) is fairly well understood, at least for sweet, umami and bitter tastes. Scientists still don't have a clear understanding of what turns off taste cells.
A new study focusing on the “taste terminator protein” may help answer some of these questions: Why are some people so sensitive to bitter tastes? Why do other people barely notice them? And how do we stop tasting altogether?
In a study published online in PLoS ONE, researchers from Monell Center and Givaudan Flavors identified a protein called Serca3 as a key agent in shortening and/or turning off the bitter taste signal entirely.
The study, which was conducted on mice, found that the mice that lacked the gene for Serca3 were more sensitive, and hence more averse, to bitter tastes. So if you sip a gin and tonic water, and the quinine pops on your palate like a hammer to the tongue, don't blame Canada Dry, blame your lack of a Serca3 gene.
The study primarily focused on bitter tastes, but scientists found that mice without Serca3 also responded to sweet and umami tastes as being slightly more intense when compared to the responses of normal mice. There were no changes for salty and sour tastes. Perhaps these findings help explain the legendary species of mice supertasters.
Future studies will explore the role of Serca2 in regulating sweet and umami taste perception.