Bitter taste

The ability to detect bitter tastes is thought to help us to avoid eating toxic substances. In an Advanced Online Publication in Nature Genetics, Bufe et al. describe the characterization of a human bitter-taste receptor (Nature Genetics, 15 October 2002, doi:10.1038/ng1014). They mined human genome sequence information and found 24 intronless genes encoding potential TAS2R taste receptors; they expressed each of these in tissue culture cells and recorded calcium transients using a fluorescence imaging plate reader. This led to the identification of one receptor, TAS2R16, that recognized the bitter tastes of beta-glycopyranoside phytonutrients such as salicin, an extract from willow bark that is used as an analgesic. TAS2R16 is expressed in human taste buds of the villate papillae, and Bufe et al. found evidence for receptor desensitization upon repeated exposure and adaptation. Compounds recognised by TAS2R16 have a common chemical structure, which might explain the breadth of taste perception. These results offer a taste of things to come, as researchers explore the function of the other TAS2R receptors in the human genome.