The composition and stoichiometry of bitter taste receptors is not yet established. Bitter receptors appear to separate into two groups, with very restricted ligand specificity or much broader responsiveness. For example, T2R5 responded to cycloheximide, but not 10 other bitter compounds [2], while T2R14 responded to at least eight different bitter tastants, including (-)-α-thujone and picrotoxinin [1].

Specialist database BitterDB contains additional information on bitter compounds and receptors [6].

* Key recommended reading is highlighted with an asterisk

* Palmer RK. (2019) A Pharmacological Perspective on the Study of Taste. Pharmacol Rev, 71 (1): 20-48. [PMID:30559245]

1. Behrens M, Brockhoff A, Kuhn C, Bufe B, Winnig M, Meyerhof W. (2004) The human taste receptor hTAS2R14 responds to a variety of different bitter compounds. Biochem Biophys Res Commun, 319 (2): 479-85. [PMID:15178431]

2. Chandrashekar J, Mueller KL, Hoon MA, Adler E, Feng L, Guo W, Zuker CS, Ryba NJ. (2000) T2Rs function as bitter taste receptors. Cell, 100 (6): 703-11. [PMID:10761935]

3. Kim D, An SS, Lam H, Leahy JW, Liggett SB. (2020) Identification and Characterization of Novel Bronchodilator Agonists Acting at Human Airway Smooth Muscle Cell TAS2R5. ACS Pharmacol Transl Sci, [Epub ahead of print]. DOI: 10.1021/acsptsci.0c00127

4. Kinghorn AD, Pan L, Fletcher JN, Chai H. (2011) The relevance of higher plants in lead compound discovery programs. J Nat Prod, 74 (6): 1539-55. [PMID:21650152]

5. Slack JP, Brockhoff A, Batram C, Menzel S, Sonnabend C, Born S, Galindo MM, Kohl S, Thalmann S, Ostopovici-Halip L et al.. (2010) Modulation of bitter taste perception by a small molecule hTAS2R antagonist. Curr Biol, 20 (12): 1104-9. [PMID:20537538]

6. Wiener A, Shudler M, Levit A, Niv MY. (2012) BitterDB: a database of bitter compounds. Nucleic Acids Res, 40 (Database issue): D413-9. [PMID:21940398]