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. 1998 Nov 10;95(23):13947–13952. doi: 10.1073/pnas.95.23.13947

Figure 6.

Figure 6

I1760 is required for irreversible binding of BTX to the sodium channel. After BTX modification, the membrane potential was held at −120 mV, and 5-ms test pulses to 0 mV were applied once every 30 s (see Inset). (A) Representative current traces from a type IIA sodium channel at 0 and 840 s after repolarization to −120 mV. Note that there is little reversal of the BTX effect after holding the channel in the closed conformation for 15 min. (B) Representative current traces from a mutant I1760A channel 0 s before and 840 s after repolarization to −120 mV. For this mutant, BTX modification is more rapidly reversible. (C) Rate of reversal of the effect of BTX at −120 mV for WT (filled circles) and mutant (open circles) sodium channels. Normalized sodium current recorded at the end of each 50-ms test pulse is plotted versus time at −120 mV.