Functional properties of the WT_E654Q concatemer. (A) Representative currents of the WT_E654Q concatemer at 80 and −80 mV. Blue and red dots indicate the reference pulses used for rundown correction at 80 and −80 mV, respectively (see Materials and methods). (B) Rundown-corrected concentration–response relations of the WT_E654Q concatemer at 80 and −80 mV (n = 4–10 for each data point). Lines are the best fit to a biphasic Hill equation. Dashed lines indicate the relations of WT_WT at 80 and −80 mV. (C) Na⁺ versus Cl⁻ selectivity of the WT_E654Q concatemer. (left and middle) I-V plots recorded at 150 mM extracellular and the indicated intracellular NaCl concentrations at 2 µM (n = 6) and 1 mM (n = 6–7) [Ca²⁺]_free. (right) Relation between intracellular [NaCl] and E_rev at 2 µM (n = 6) and 1 mM (n = 6–7) [Ca²⁺]_free. The line indicates the Nernst potential of Cl⁻. (D, left and middle) Merged and averaged variance-<I> plots of the WT_E654Q concatemer obtained at 2 µM (n = 6) and 1 mM (n = 8) [Ca²⁺]_free at 80 mV. The dotted lines indicate the mean P_{O max} across patches. (right) Pooled data of individual i and P_{O max} values obtained from individual patches expressing the WT_E654Q concatemer at 2 µM (n = 6) and 1 mM (n = 8) [Ca²⁺]_free. n.s., P > 0.05; ***, P ≤ 0.001. In B–D, data are presented as mean and errors as SEM.