Bitter taste receptor (PubMed:25796330). Binds quinine, dextromethorphan, diphenhydramine, diphenidol, chlorpheniramine, diphenidol, chloramphenicol, chloroquine and coumarin, this latter being a weak agonist, as well as epiquinidine, ethylhydrocupreine and quinidine (PubMed:28811548). Expressed in the oral cavity, as well as in the gastrointestinal tract, including in the upper palate, tongue, proventriculus, ventriculus, duodenum, jejunum, ileum, cecum and colon. Belongs to the G-protein coupled receptor T2R family.