Fig. 4.

Role of the R domain in [Cl⁻]_o sensing by CFTR. a, c Representative fWCR current recordings measured between ±100 mV in 20 mV steps from HEK cells transfected with deltaR-CFTR or deltaR-E1371S CFTR as indicated. Note all experiments used unstimulated conditions. The current traces are from the top down: (i) unstimulated in 155.5 mM [Cl⁻]_o, (ii) unstimulated in 35.5 mM [Cl⁻]_o and (iii) unstimulated in 155.5 mM [Cl⁻]_o. Dotted line to the right of the current traces indicates zero current level. b, d Representative I-V plots for the data presented in a and c. e Percentage current stimulation by [Cl⁻]_o for WT CFTR (n = 24) and for DeltaR and DeltaR-E1371Q mutants (see Fig. 1) under unstimulated (No Stim) or after exposure to a combination of forskolin and genistein (FSK/Genistein). (n = 4–10). Data are means ± SEM. *p < 0.05, **p < 0.01 compared to indicated datasets