Fig. 4.
Frog Tas2rs response to bitter peptides and bile acids. The frog bitter taste receptors Tas2r5, Tas2r9a, Tas2r11, Tas2r20, Tas2r29, and Tas2r37 were transiently transfected into HEK 293T-Gα16gust44 cells and subjected to functional calcium-mobilization experiments using a FLIPRTETRA. The receptors were stimulated either with l-Trp-Trp-Trp (gray bars, left side of panel) or the bile acids cholic acid (CA, black bars) and glycocholic acid (GCA, white bars) (right side of panel). The concentrations used for stimulation are depicted on the left (l-Trp-Trp-Trp in µM) and right (CA and GCA in mM) columns. The corresponding Tas2rs are indicated in the center of the figure. Cells transfected with empty vector served as negative controls (see supplementary information). The relative changes in fluorescence upon substance application (ΔF/F) were monitored (scale bars are shown at the bottom left and right). Data represent mean ± SEM of three independent experiments, each performed in duplicates. *p < 0.05, (two-sided) student’s t-test