Figure 1.
Figure 1. Biophysical properties of NaChBac WT expressed in High 5 insect cells. (A) Representative ionic currents measured from NaChBac WT. The cell was held at −120 mV, and 300-ms depolarizations were applied to potentials from −120 to 50 mV in 10-mV increments. (B) I-V curve of NaChBac WT. (C) Voltage dependence of activation of NaChBac WT measured from peak tail currents with a V1/2 = −36.6 ± 0.8 mV (n = 4). (D) G-V curves of WT, R1C, R2C, and R3C mutants derived from peak I-V relationships. The voltages for half-maximal channel activation and slope are WT: V1/2 = −36.6 ± 0.8 mV, k = 7.00 ± 0.10 mV; R1C: V1/2 = −22.2 ± 2.3 mV, k = 6.00 ± 0.62 mV; R2C: V1/2 = −28.6 ± 0.7 mV, k = 10.39 ± 2.13 mV (P < 0.05 vs. WT); and R3C: V1/2 = −37.8 ± 0.1 mV, k = 3.80 ± 0.12 mV (P < 0.05 vs. WT). (E) Recovery from inactivation of NaChBac WT. The cells were held at −120 mV, and a 2.5-s inactivation pulse to −10 mV was applied. A variable recovery interval was followed by a 1.5-s test pulse (protocol, top). (middle) Example superimposed current records are shown with the record from the trace with longest recovery interval shown in red. (bottom) Peak test pulse current was plotted versus recovery interval. Recovery from inactivation was best fit with a double exponential equation where τ1 = 0.2 s, 73% of current and τ2 = 1.34 s, 27% of current (n = 7). (F) Gating currents of NaChBac WT. Gating currents were measured using holding potentials of −80 or 0 mV. When the holding potential was −80 mV, a short (30 ms) prepulse to −150 mV was followed by 20-ms steps to more positive potentials in 10-mV increments before returning to −150 mV for 20 ms. When the holding potential was 0 mV, 20-ms pulses were applied to more hyperpolarized potentials. (top) Examples of gating current traces measured using the −80-mV holding potential (left) or the 0-mV holding potential (right). (bottom) Q-V relationships. The Q-V relationship measured from a holding potential of −80 mV has a V1/2 = −86.9 ± 1.7 mV, k = 15.8 ± 0.6 mV (n = 5); that measured from a holding potential of 0 mV has a V1/2 = −127.8 ± 5.6 mV, k = 14.4 ± 1.2 mV (n = 5). Error bars represent SEM.

Biophysical properties of NaChBac WT expressed in High 5 insect cells. (A) Representative ionic currents measured from NaChBac WT. The cell was held at −120 mV, and 300-ms depolarizations were applied to potentials from −120 to 50 mV in 10-mV increments. (B) I-V curve of NaChBac WT. (C) Voltage dependence of activation of NaChBac WT measured from peak tail currents with a V1/2 = −36.6 ± 0.8 mV (n = 4). (D) G-V curves of WT, R1C, R2C, and R3C mutants derived from peak I-V relationships. The voltages for half-maximal channel activation and slope are WT: V1/2 = −36.6 ± 0.8 mV, k = 7.00 ± 0.10 mV; R1C: V1/2 = −22.2 ± 2.3 mV, k = 6.00 ± 0.62 mV; R2C: V1/2 = −28.6 ± 0.7 mV, k = 10.39 ± 2.13 mV (P < 0.05 vs. WT); and R3C: V1/2 = −37.8 ± 0.1 mV, k = 3.80 ± 0.12 mV (P < 0.05 vs. WT). (E) Recovery from inactivation of NaChBac WT. The cells were held at −120 mV, and a 2.5-s inactivation pulse to −10 mV was applied. A variable recovery interval was followed by a 1.5-s test pulse (protocol, top). (middle) Example superimposed current records are shown with the record from the trace with longest recovery interval shown in red. (bottom) Peak test pulse current was plotted versus recovery interval. Recovery from inactivation was best fit with a double exponential equation where τ1 = 0.2 s, 73% of current and τ2 = 1.34 s, 27% of current (n = 7). (F) Gating currents of NaChBac WT. Gating currents were measured using holding potentials of −80 or 0 mV. When the holding potential was −80 mV, a short (30 ms) prepulse to −150 mV was followed by 20-ms steps to more positive potentials in 10-mV increments before returning to −150 mV for 20 ms. When the holding potential was 0 mV, 20-ms pulses were applied to more hyperpolarized potentials. (top) Examples of gating current traces measured using the −80-mV holding potential (left) or the 0-mV holding potential (right). (bottom) Q-V relationships. The Q-V relationship measured from a holding potential of −80 mV has a V1/2 = −86.9 ± 1.7 mV, k = 15.8 ± 0.6 mV (n = 5); that measured from a holding potential of 0 mV has a V1/2 = −127.8 ± 5.6 mV, k = 14.4 ± 1.2 mV (n = 5). Error bars represent SEM.

This Feature Is Available To Subscribers Only

or Create an Account

Close Modal
Close Modal