Figure 1.

Effects of Cd²⁺ on wild-type and S6 cysteine-substituted spHCN channels. Representative recordings from inside-out patches excised from HEK293 cells expressing wild-type (WT) or mutant spHCN before (o) or during (+) application of 20 μM intracellular Cd²⁺. Dashed lines represent zero current levels. Channels were held at +10 mV, and currents were elicited by a step to −110 mV, followed by a step to +30 mV. For 459C and D471C, channels were held at +50 mV and stepped to −90 mV, and then back to +50 mV. Currents were not leak-subtracted. Time scale bar (200 ms) applies to all currents except G461C (100 ms) and N465C (400 ms). Maximum inward currents for these traces: WT, 736 pA; F459C, 101 pA; I460C, 52 pA; G461C, 142 pA; H462C, 32 pA; T464C, 761 pA; N465C, 95 pA; L466C, 221 pA; I467C, 241 pA; Q468C, 826 pA; M470C, 178 pA; and S472C, 209 pA.