Figure 1.

TAS2R14-based peptides are phosphorylated at Ser/Thr by GRK2.A, localization of the Ser/Thr in the third intracellular loop (IL3) and C-terminal tail (CT) of TAS2R14. B–D, peptides based on WT IL3 and CT, but not Ala substituted for Ser/Thr peptides, are phosphorylated by activated GRK2 (representative experiments). E, GST-IL-WT and GSTCT-WT are phosphorylated by activated GRK2 to the same extent. The phosphorylation levels were normalized to the amount of loaded protein as determined by Coomassie blue staining. The small amount of signal observed in the mutant peptide lanes was not different than “0” as determined by the one-sample t test. ∗p < 0.001 versus analogous WT peptide. Data are shown as mean ± SD, with individual results, from five independent experiments. GRK2, G protein–coupled receptor kinase 2; GST glutathione-S-transferase; TAS2R14, bitter taste 2 receptor member 14.