Effects of MTSET on S312C channels. (A) Tail currents elicited as described in Fig. 1 A. Upper family of traces is before and lower family is 8 min after exposure to 400 μM MTSET added to the trans compartment. (B) Normalized current voltage plots were generated as described in Fig. 1 B. Unreacted S312C channels (circles) behave similarly to WT channels; solid line is Boltzmann fit (Eq. 1) with a V0 = −7 mV and z = 1.3. Tail currents measured after the addition of MTSET (squares) were normalized to their maximum current. Data points represent the mean ± SEM of three experiments. (C) The addition of 400 μM MTSET trans leads to a 75% decrease in current at +20 mV and a loss of gating at negative voltages. The breaks in the record are 70 and 170 s, respectively. (D) Current trace before exposure to MTSET depicted by dotted line; trace obtained 3 min after exposure is superimposed at the same scale (solid black line) and after normalizing to the peak current at −60 mV before reaction (gray line) to emphasize effect on gating.
