Relationship of the G-V relation to the components of charge movement. (A; top) Ion currents recorded from tsA201 cells in response to 1-s voltage steps from −80 mV to between −80 and +80 mV, repolarizing to −120 mV as indicated in the protocol. (Bottom) G-V relationship: mean G-V_1/2 = −3.5 ± 6.9 mV and k = 9.7 ± 0.8 mV; n = 5. (B) Q_total-V_off from the experiment shown in Fig. 5 B, fit with a single Boltzmann relation: V_1/2 = −53.1 ± 2.6 mV and k = 18.7 ± 0.6 mV; n = 4. Q₁, Q₂, and G-V curves are shown in gray, superimposed for comparison.