SHIFT FOTO / CORBIS
In the choice of what to ingest, the sense of taste is both a guardian and a guide. The sensations of bitter and sour keep us from eating potentially toxic substances and strong acids, while the preferred qualities of sweet, umami (the “savory” taste of glutamate), and salty drive intake of carbohydrates, amino acids, and sodium, respectively. Taste sensations are mediated by taste buds—small clusters of specialized epithelial cells on the tongue, soft palate, and larynx. Over the last two decades, as scientists have uncovered the array of G protein–coupled receptor (GPCR) cascades and ion channels that underlie taste signaling, they have also discovered, to their surprise, that the expression of these receptors and channels is not limited to taste buds. Indeed, elements of the ...
