The absence of the cap structure and a ring of four tyrosines confer full sensitivity of TASK-3 channels to TEA. (A,C,E,G), whole cell recordings showing the effect of TEA (100 mM) on TASK-3/2loop2 channels. (A) TASK-3/2loop2/Y99A channels (C) TASK-3/2loop2/Y205A channels (E) and TASK-3/2loop2/Y99A/Y205A channels (G). (B,D,F,H), the graph shows the dose-response curves for extracellular TEA blockade displayed by TASK-3 channels constructs. (B) TEA inhibition curves of TASK-3/2loop2 (n = 4), TASK-3/2loop2/Y99A (D, n = 4), TASK-3/2loop2/Y205A (E, n = 3) and TASK-3/2loop2/Y99A/Y205A (H, n = 3) mutant channels. Results are shown as means ± SEM. Curves are fits to a 4-parameter logistic function and were constructed by using the average of fitted parameters of the individual experiments. The lines without points are taken from the fits shown in Figure 1C and correspond to the TEA inhibition curves for TASK-3 WT and Kv2.1, respectively.