Effects of MTS Reagents on ASIC3E79C Channels at Neutral pH. (A) Models showing the structural similarity between MTSEA and AGM in activating ASIC3. (B) Sample traces showing effects of MTSEA (0.2 mM) on ASIC3E79C (upper trace) and ASIC3E423C mutated channels (lower traces) at pH 7.4. Similar results were obtained from other four measurements. (C) Sample traces showing a lack of effects of MTSET (0.5 mM) on ASIC3E79C. (D) Maximal currents induced in ASIC3E79C by MTSEA (0.2 mM, 2 min) and MTSET (0.5 mM, 5-10 min). Data points are means ± S.E.M. of five measurements normalized to pH 5.0-induced peak currents. **p < 0.001 vs. baseline level. #indicates no detectable changes upon exposure to MTSET (0.5 mM, 5-10 min).