T2R9 Activators

Chemical activators of T2R9 include a variety of compounds that are recognized for their bitterness, and these activators interface with the protein to initiate a cascade of signaling events. Allyl isothiocyanate, a compound known for its pungent taste in mustard and wasabi, activates T2R9 by binding directly to the receptor, causing a conformational change that triggers the signaling related to bitter taste perception. This is a common characteristic of compounds containing thiourea and isothiocyanate moieties, which are known to activate bitter taste receptors. Similarly, caffeine, a bitter compound ubiquitous in coffee and tea, activates T2R9 by directly interacting with the receptor, the engagement of which leads to the initiation of a gustatory signal transduction cascade. Quinine, a compound known for its bitter taste in tonic water, directly engages T2R9, causing the perception of bitterness, a hallmark function of T2R9. Denatonium benzoate, recognized as one of the most bitter compounds synthetically available, binds and activates T2R9, leading to downstream signaling in taste receptor cells.

Continuing the list of T2R9 activators, propylthiouracil, a thiourea-like structure, activates T2R9 through direct interaction, resulting in the activation of taste signaling pathways. Parthenolide and absinthin, both of which possess sesquiterpene lactone structures, are known to activate T2R9 by engaging directly with the receptor, causing a signaling cascade associated with the detection of bitter taste. Sucrose octaacetate, despite its name suggesting sweetness, is intensely bitter and directly activates T2R9, leading to signal transduction in taste receptor cells. Salicin, a bitter glucoside, activates T2R9, resulting in the transduction of signals that culminate in the perception of bitterness. Nicotine, an alkaloid with a bitter taste, also activates T2R9 by direct interaction, involving the receptor in signal pathways pertinent to taste. Colchicine, an alkaloid compound, activates T2R9 due to the protein's capacity to interact with similar structures, leading to the bitter taste signal transduction. Lastly, amarogentin, noted for being one of the most bitter substances, activates T2R9 by directly binding to it, thus fitting within the spectrum of bitter compounds that T2R9 is responsive to. Each of these chemicals activates T2R9 by directly binding to the receptor, without requiring any upregulation of expression or transcriptional activation, ensuring that the activation is a direct consequence of the chemical-protein interaction.