Figure 2

I–V relationships and activation τs of Kv currents in Kv2.1 mutant-transfected Neuro2a cells.

(A) Representative currents in cells transfected with WT Kv2.1, empty vector, R306C and G401R mutants of Kv2.1. All currents were elicited with the voltage steps in 10 mV increments from the holding potential of −70 mV, as depicted above the WT trace. (B) Currents in untransfected cells (no vector). (C) Currents in empty were abolished by bath application of 100 nM GxTX. (D) I–V relationship of peak current densities during voltage steps. The relationship in WT (solid squares) is shown in the right panel on a larger scale because of its greater magnitude. The relationship in no vector (open circles) was not statistically different from that in empty (solid circles, P = 0.90 for current density at +50 mV), whereas R306C (solid diamonds), G401R (solid triangles) and GxTX (open triangles) were significantly different from empty at a current density of +50 mV (P = 0.025 vs R306C, P < 0.01 vs G401R and GxTX by Dunnett’s T3 test). The numbers of cells analyzed are indicated in parentheses. (E) Voltage dependence of activation τ. τs in empty and WT were determined by fitting the initial current rising phase from 20% of the peak rise to single exponentials. Currents in R306C were similarly fitted to double exponentials and the initial faster τs plotted. τs at −30 and −20 mV in R306C were smaller than in WT (P < 0.01 by Dunnett’s T3 test), whereas at +50 mV it was larger than in WT (P < 0.01 by REGW test).