Oral and extra-oral taste perception.

Of the five basic taste qualities, the molecular mechanisms underlying sweet, bitter, and umami (savory) taste perception have been extensively elucidated, including the taste receptors and downstream signal transduction molecules. Recent studies have revealed that these taste-related molecules play important roles not only in the oral cavity but also in a variety of tissues including the respiratory tract, stomach, intestines, pancreas, liver, kidney, testes, and brain. This review covers the current knowledge regarding the physiological roles of taste-related molecules in the oral and extra-oral tissues.