Fig. 2: Recognition of AAI in the orthosteric binding pocket of TAS2R43.
From: Structural insights into coffee bitter taste perception by TAS2R43 receptor
a, A representative 3D reconstruction model for the Gi-coupled TAS2R43. TAS2R43 and Gαi are colored orange and purple, respectively. A model-fitted map of AAI in the orthosteric pocket is colored magenta. b, Extracellular view of AAI-bound orthosteric binding pocket. F2526.59, a potential lid for ligand sensing, is indicated by a green stick. c, An enlarged view of the AAI-interacting residues indicated by sticks. Hydrogen bonds and ionic interactions are shown as black dashed lines. Models for water molecules are shown as red spheres, with their cryo-EM densities indicated by mesh. d, A dose–response cAMP GloSensor assay stimulated by AAI in HEK293T cells transfected by TAS2R43 of WT and mutant AAI-interacting residues. Data represent the mean ± s.e.m. of n = 3 biological replicates. e,f, AAI-stimulated dose–response BRET2 assays for Gi1 (e) and Ggust (f) using TAS2R43 mutants at the orthosteric pocket. g, Orthogonal views of TAS2R43 representing electrostatic potential surface calculation. Left, same view from a. Red, negative (−5 kT/e); blue, positive (+5 kT/e). AAI is indicated by a magenta stick. h,i, TAS2R43 was activated by coffee compounds in dose–response BRET assays for Gi1 (h) and Ggust (i) using HEK293T cells. The values were normalized to AAI. Data represent the mean ± s.e.m. of n = 4 biological replicates. All of the pEC50 and Emax values for dose–response functional assays are provided in Supplementary Tables 2–4 (d–f,h,i).
