Effect of mutations at position 9′ of M2 on deactivation of ELIC. (A–E) Macroscopic current responses to 500-ms pulses of 10 mM cysteamine recorded at –80 mV from wild-type ELIC and the indicated mutants in the outside-out configuration. The solutions flowing through the two barrels of the perfusion tubing were (in mM) 142 KCl, 5.4 NaCl, 1.8 CaCl2, 1.7 MgCl2, and 10 HEPES/KOH, pH 7.4 with or without cysteamine. The insets emphasize the time courses of deactivation; lines are fits to monoexponential-decay functions. (F) Mutant-construct deactivation time constants obtained from monoexponential fits normalized to the wild-type time constant. The plotted values are means obtained from 6 patches for each mutant; error bars are the corresponding standard errors. All current traces shown in this figure are the averages of 10 consecutive responses recorded from representative patches.
