Figure 5. The residues Cys621, Glu625 and Tyr 658 in the channel coupling domain critical for DNFB binding. (a) Representative bound conformations of DNFB confined to the pocket consisting of three short helixes (H2, H4 and H5) in the coupling domain in the side view (left) and the top-down view (right). (b) Local view of a DNFB and a TRPA1 subunit interactions from hydrogen bonds (green), π-Alkyl (pink) and π-sulfur (black) are shown as dotted lines. Halogen bond is circled in red. (c-g) Representative current traces of wild type mouse TRPA1 (c), C621G (d), E625A (e), Y658A (f) and E681A (g) mutants expressed in HEK293 cells in responses to DNFB and AITC. (h) Summary for normalized WT TRPA1 or mutant channel current activation by 10 µM DNFB and 300 µM AITC, shown by ratio of DNFB current to AITC current (n = 5). Data are shown as the mean ± SEM. *P< 0.05, ***P< 0.001, by unpairedt -test.