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. 2016 Mar 10;6:22807. doi: 10.1038/srep22807

Figure 3. Histidine residues in hTAS1R2 are required for taste-modifying effect of MCL.

Figure 3

(a) HEK293 cells were transiently transfected with hTAS1R2 (WT or mutant), hTAS1R3, and Gα16-gust44. The responses of the receptors to 0.3 mM SC45647 (SC), 10 mM saccharin (Sac), 10 mM aspartame (Asp), 30 mM cyclamate (Cyc) and 3 mM citric acid (CA: pH 5.0) after application of MCL (10 μg/ml) were examined. 15–30 cells. Responses to test solutions were analyzed by multivariate ANOVA followed by Tukey-Kramer test. *P < 0.05, **P < 0.01, ***P < 0.001 vs. WT. (b) A snake plot of hTAS1R2. Histidine residues in hTAS1R2 are indicated in red. ATD, Amino-terminal domain; CRD, cysteine-rich domain (shown in yellow); TMD, transmembrane domain. (c) HEK293 cells were transiently transfected with hTAS1R2, hTAS1R3, and Gα16-gust44. The extracellular pH (pHo) dependent responses of the receptors to 3 mM citric acid (CA) and 7 mM HCl after application of MCL (10 μg/ml) were examined. 18 cells. (d) HEK293 cells were transiently transfected with hTAS1R2H590A, hTAS1R3 and Gα16-gust44. The pHo-dependent responses of the receptors to 3 mM CA and 7 mM HCl after application of MCL (10 μg/ml) were examined. 15–19 cells. (e) Intracellular pH (pHi) of HEK293 cells was measured after application of different pH (pHo) of 3 mM CA and 7 mM HCl. 145–148 cells. (f) Intracellular pH response curves were obtained by using the same solutions of 3 mM citric acid and 7 mM HCl in (c). 18 cells. Values are means ± S.E.