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Figure 5—figure supplement 1. Mutation hE1371Q strongly stabilizes, whereas hD1370N destabilizes, bursts in other non-hydrolytic backgrounds. (A) Close-up view of the site 2 interface in the OF structure of hCFTR-E1371Q (PDBID: 6msm) highlighting (in sticks) NBD1 D-loop residue hG576 (orange), and NBD2 residues hQ1371 (black), hD1370 (gray), and hK1250 (gray). ATP, yellow sticks; Mg2+, purple sphere. (B, D), Macroscopic current relaxations following ATP removal for indicated CFTR channel mutants (color coded). Experiments were performed as in Figure 3A, and current amplitudes are shown normalized by their steady-state values in ATP (i.e., just before ATP removal). (C, E), Relaxation time constants of the currents in (B, D), obtained by fits to single exponentials, displayed on a logarithmic ordinate. Data show mean ± standard error of the mean (SEM) from five to eight experiments.