Figure 7.
Figure 7. Functional properties of the K588E_E702Q and the WT_K588E/E702Q concatemers. (A) Merged and averaged variance-<I> plot and pooled data (n = 5) of the K588E mutant obtained at 2 µM [Ca2+]free at 80 mV. (B, left) Representative currents of the K588E/E702Q double mutant at 80 and −80 mV. (right) I-V plots recorded at symmetrical 150 mM NaCl for WT (n = 8) and the K588E/E702Q double mutant (n = 13) at 1 mM [Ca2+]free. (C) Rundown-corrected concentration–response relations of the K588E/E702Q double mutant at 80 and −80 mV (n = 10 for each data point). Solid lines are the best fit to the Hill equation. Dashed lines indicate the relations of E702Q at 80 and −80 mV. (D) Merged and averaged variance-<I> plot and pooled data (n = 9) of the K588E/E702Q double mutant obtained at 1 mM [Ca2+]free at 80 mV. (A [middle] and D [left]) The dotted lines indicate the mean PO max across patches. (A and D, right) Dotted lines indicate the corresponding value of WT mTMEM16A. (E) Na+ versus Cl− selectivity of the K588E/E702Q double mutant. (left) I-V plots recorded at 150 mM extracellular and the indicated intracellular NaCl concentrations at 1 mM (n = 7–13) [Ca2+]free. (right) Relation between intracellular [NaCl] and Erev at 1 mM (n = 7–13) [Ca2+]free. The line indicates the Nernst potentials of Cl−. (F) Representative currents of the K588E_E702Q concatemer at 80 and −80 mV. (G) Representative currents of the WT_K588E/E702Q concatemer at 80 and −80 mV. (B, F, and G) Blue and red dots indicate the reference pulses used for rundown correction at 80 and −80 mV, respectively (see Materials and methods). (H) Rundown-corrected concentration–response relation of the K588E_E702Q (n = 7–19 for each data point) and WT_K588E/E702Q (n = 10–21 for each data point) concatemer at 80 mV. Solid lines are the best fit to a biphasic Hill equation. Dashed line indicates the relation of the WT_E702Q concatemer at 80 mV. (I) Rundown-corrected concentration–response relations of the K588E_E702Q concatemer at 80 and −80 mV (n = 7–19 for each data point). Lines are the best fit to biphasic (80 mV) and monophasic (−80 mV) equations. (J) Rundown-corrected concentration–response relations of the WT_K588E/E702Q concatemer at 80 and −80 mV (n = 10–21 for each data point). Lines are the best fit to a biphasic Hill equation. In A–E and H–J, data are presented as mean and errors as SEM.

Functional properties of the K588E_E702Q and the WT_K588E/E702Q concatemers. (A) Merged and averaged variance-<I> plot and pooled data (n = 5) of the K588E mutant obtained at 2 µM [Ca2+]free at 80 mV. (B, left) Representative currents of the K588E/E702Q double mutant at 80 and −80 mV. (right) I-V plots recorded at symmetrical 150 mM NaCl for WT (n = 8) and the K588E/E702Q double mutant (n = 13) at 1 mM [Ca2+]free. (C) Rundown-corrected concentration–response relations of the K588E/E702Q double mutant at 80 and −80 mV (n = 10 for each data point). Solid lines are the best fit to the Hill equation. Dashed lines indicate the relations of E702Q at 80 and −80 mV. (D) Merged and averaged variance-<I> plot and pooled data (n = 9) of the K588E/E702Q double mutant obtained at 1 mM [Ca2+]free at 80 mV. (A [middle] and D [left]) The dotted lines indicate the mean PO max across patches. (A and D, right) Dotted lines indicate the corresponding value of WT mTMEM16A. (E) Na+ versus Cl− selectivity of the K588E/E702Q double mutant. (left) I-V plots recorded at 150 mM extracellular and the indicated intracellular NaCl concentrations at 1 mM (n = 7–13) [Ca2+]free. (right) Relation between intracellular [NaCl] and Erev at 1 mM (n = 7–13) [Ca2+]free. The line indicates the Nernst potentials of Cl−. (F) Representative currents of the K588E_E702Q concatemer at 80 and −80 mV. (G) Representative currents of the WT_K588E/E702Q concatemer at 80 and −80 mV. (B, F, and G) Blue and red dots indicate the reference pulses used for rundown correction at 80 and −80 mV, respectively (see Materials and methods). (H) Rundown-corrected concentration–response relation of the K588E_E702Q (n = 7–19 for each data point) and WT_K588E/E702Q (n = 10–21 for each data point) concatemer at 80 mV. Solid lines are the best fit to a biphasic Hill equation. Dashed line indicates the relation of the WT_E702Q concatemer at 80 mV. (I) Rundown-corrected concentration–response relations of the K588E_E702Q concatemer at 80 and −80 mV (n = 7–19 for each data point). Lines are the best fit to biphasic (80 mV) and monophasic (−80 mV) equations. (J) Rundown-corrected concentration–response relations of the WT_K588E/E702Q concatemer at 80 and −80 mV (n = 10–21 for each data point). Lines are the best fit to a biphasic Hill equation. In A–E and H–J, data are presented as mean and errors as SEM.

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