Why bitter tastes differ for some people

August 3, 2011

New findings may lend insight into why some people are especially sensitive to bitter tastes. Scientists from the Monell Center and Givaudan Flavors have identified a protein inside of taste cells that acts to shorten bitter taste signals. They further report that mice lacking the gene for this taste terminator protein are more sensitive to bitter taste and also find it more aversive, possibly because they experience the taste for a longer period of time.

When you drink tonic water, quinine molecules activate or “turn on” your taste receptor cells. The activated cells then send messages to tell your brain that the tonic is bitter. The mechanisms that “turn on” taste cells are fairly well understood, at least for sweet, umami, and bitter tastes. The researchers wanted to know: what turns the taste cells off? In the study, published online in the open access journal PLoS ONE, the researchers used multiple approaches to identify a protein called Serca3 and demonstrate that it plays an important role in turning off the bitter taste signal.

To demonstrate how Serca3 influences taste, the researchers went on to show that mice bred to lack the Serca3 gene were more sensitive to bitter taste and also found it more unpleasant. This response was primarily related to bitter taste. However, mice without Serca3 also responded to sweet and umami tastes as being slightly more intense as compared to the responses of normal mice. There were no changes for salty and sour tastes.

The Serca3 protein functions as a calcium pump. It helps to terminate bitter taste signals by removing calcium from the cell, which then causes the cell to stop signaling. The researchers suspect that another member of the Serca family may work in a similar way to terminate taste sensations in sweet and umami cells. Future studies will investigate the contribution of this component, Serca2, in regulating sweet and umami taste perception.

Abstract