Figure 2.

MTSEA modification of A384C channels. (A) Open state MTSEA modification. Following channel closing and reopening in 10 μM Ca²⁺ to verify rapid solution exchange, open channels were exposed to 200 μM MTSEA (thick line) for 60 s and current decay monitored. Holding potential was −80 mV in symmetrical K⁺. Currents were inverted in A–C. (B) Closed state MTSEA modification. Following channel closing (c) and reopening (o), channels were closed for 2 s, MTSEA applied in the closed state for 5 s, and the channels washed for 2 s in “0” Ca²⁺ solution before opening for 3 s to monitor the fraction of current modified. This closed state procedure was repeated 11 times to saturate modification. (C) Time course of modification for the representative patches shown in A and B, currents normalized to control and plotted versus time (line, open) or cumulative MTSEA exposure (open symbol, closed). Single exponential fits are overlaid with each plot. (D) Average MTSEA modification rates determined from time course of modification in the open or closed state.