Receptor that may play a role in the perception of bitterness and is gustducin-linked. May play a role in sensing the chemical composition of the gastrointestinal content. The activity of this receptor may stimulate alpha gustducin, mediate PLC-beta-2 activation and lead to the gating of TRPM5 (By similarity). Activated by the sulfonyl amide sweeteners saccharin and acesulfame K. Expressed in subsets of taste receptor cells of the tongue and exclusively in gustducin-positive cells. 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.