Bitter taste TAS2R14 activation by intracellular tastants and cholesterol.

Bitter taste receptors, particularly TAS2R14, play central roles in discerning a wide array of bitter substances, ranging from dietary components to pharmaceutical agents 1,2 . TAS2R14 is also widely expressed in extra-gustatory tissues, suggesting its additional roles in diverse physiological processes and potential therapeutic applications 3 . Here, we present cryo-electron microcopy structures of TAS2R14 in complex with aristolochic acid, flufenamic acid and compound 28.1, coupling with different G protein subtypes. Uniquely, a cholesterol molecule is observed occupying what is typically an orthosteric site in class A GPCRs. The three potent agonists bind, individually, to the intracellular pockets, suggesting a distinct activation mechanism for this receptor. Comprehensive structural analysis, combined with mutagenesis, and molecular dynamic simulations studies, illuminate the receptor's broad-spectrum ligand recognition and activation via intricate multiple ligand-binding sites. Additionally, our study uncovers the specific coupling modes of TAS2R14 with gustducin and G i1 proteins. These findings should be instrumental in advancing our knowledge underlying bitter taste perception and its broader implications in sensory biology and drug discovery.