SCAM experiments using different MTS reagents show robust and differential effects on G45C. (A and B) The effects of MTS reagents on hemichannel currents are shown from G45C (A) and A40C (B) recorded at −40 mV. Before the recordings shown, oocytes were exposed to a solution containing 3 mM EGTA (0 Ca²⁺) to open hemichannels and then were exposed to the same solution containing 0.2 mM MTSET (positively charged, left) or 2.0 mM MTSES (negatively charged, right). G45C currents showed rapid and robust response to both MTS reagents that were opposite in sign, decreasing for MTSET and increasing for MTSES. Both MTS reagents decreased A40C currents, but the effects were more modest and slow in time course. (C) Summary of the percent change in current (mean ± SEM) upon application of the MTS reagent. n = 5 for WT Cx26, n = 7 for A40C, and n = 24 for G45C for MTSET. n = 7 for WT Cx26, n = 7 for A40C, and n = 23 for G45C for MTSES.