Effects of DHA and MTSEA⁺ at pH 7.4 on WT-IR and three mutations. Graphs display representative G-V curves with current traces as insets for voltages corresponding to 10% of G_max in control solution. Eq. 2 is used for the fit. (A) Data for WT-IR. 70 µM DHA shifts the control curve for WT-IR with −4.7 mV (left). V_1/2 = −42.8 and −47.5 mV, and s = 16.1 mV. MTSEA⁺ modification does not shift the control curve (middle). V_1/2 = −38.9 and −38.9 mV, and s = 7.4 mV. The DHA-induced shift is not affected by MTSEA⁺ modification (right). V_1/2 = −39.7 and −45.4 mV, and s = 8.2 mV. (B) Data for F416C. 70 µM DHA shifts the control curve for F416C with −2.8 mV (left). V_1/2 = −45.7 and −48.5 mV, and s = 14.0 mV. MTSEA⁺ modification shifts the control curve with +28.2 mV (middle). V_1/2 = −46.2 and −18.0 mV, and s = 14.0 mV. The DHA-induced shift is not affected by MTSEA⁺ modification (right). V_1/2 = −18.0 and −21.8 mV, and s = 14.0 mV. (C) Data for I360C. 70 µM DHA shifts the control curve for I360C with −3.1 mV (left). V_1/2 = −33.5 and −36.6 mV, and s = 8.7 mV. MTSEA⁺ modification shifts the control curve with +8.8 mV (middle). V_1/2 = −34.7 and −25.9 mV, and s = 12.4 mV. The DHA-induced shift is increased to −8.5 mV after modification (right). V_1/2 = −27.3 and −35.8 mV, and s = 16.1 mV. (D) Data for I325C. 70 µM DHA shifts the control curve for I325C with −2.9 mV (left). V_1/2 = −40.1 and −43.0 mV, and s = 17.2 mV. MTSEA⁺ modification shifts the control curve with +16.9 (middle). V_1/2 = −39.4 and −22.5 mV, and s = 13.7 mV. The DHA-induced shift is increased to −4.4 after modification (right). V_1/2 = −22.6 and −27.0 mV, and s = 13.5 mV.