Gustducin-coupled receptor immplicated in the perception of bitter compounds in the oral cavity and the gastrointestinal tract. Signals through PLCB2 and the calcium-regulated cation channel TRPM5. Activated by the sulfonyl amide sweeteners saccharin and acesulfame K. In airway epithelial cells, binding of bitter compounds increases the intracellular calcium ion concentration and stimulates ciliary beat frequency. May act as chemosensory receptors in airway epithelial cells to detect and eliminate potential noxious agents from the airways (By similarity). In airway epithelial cells, localizes to motile cilia. Expressed in subsets of taste receptor cells of the tongue and exclusively in gustducin-positive cells. Expressed in airway epithelia. Most taste cells may be activated by a limited number of bitter compounds; individual taste cells can discriminate among bitter stimuli. Belongs to the G-protein coupled receptor T2R family. A tail of protection - Issue 119 of July 2010