Effects of various thiol reagents on Panx1 F54C currents. Oocytes expressing Panx1 F54C were held at −60 mV and pulses to +60 (A) or +20 mV (B–E) were applied to activate the channel. To test for cysteine accessibility, 10 µM MBB (A), 1 mM MTSET (B), 1 mM MTSET followed by 2 mM dithiothreitol (DTT; C), 1 mM MTSES (D), 1 mM MTSBn (E), 100 µM pyrenyl maleimide (F), or 100 µM MTS-fluorescein (G) was applied.