Table 1.

Median voltage of activation, VM, and the net free energy of activation of mutants of the Shaker KV channel

Mutant VM (±SEM) n ΔGnet (±SEM) 
 mV  kcal 
WT −44.7 (±1.0) −13.6 (±0.3) 
R394A −34.6 (±1.0) −14.0 (±0.3) 
E395A −64.6 (±0.9) −19.6 (±0.3) 
V476A −61.0 (±0.9) −18.5 (±0.2) 
Y485A −47.9 (±0.9) −14.5 (±0.3) 
R394A-E395A −51.0 (±0.9) −15.5 (±0.3) 
R394A-Y485A −27.4 (±0.9) −8.3 (±0.3) 
E395A-Y485A −50.5 (±1.0) −15.3 (±0.3) 
E395A-V476A −78.8 (±1.4) −23.9 (±0.4) 
V476A-Y485A −61.4 (±1.6) −18.6 (±0.5) 
R394A-E395A-Y485A −40.0 (±1.9) −12.1 (±0.6) 
E395A-V476A-Y485A −66.6 (±0.6) −20.2 (±0.2) 
Mutant VM (±SEM) n ΔGnet (±SEM) 
 mV  kcal 
WT −44.7 (±1.0) −13.6 (±0.3) 
R394A −34.6 (±1.0) −14.0 (±0.3) 
E395A −64.6 (±0.9) −19.6 (±0.3) 
V476A −61.0 (±0.9) −18.5 (±0.2) 
Y485A −47.9 (±0.9) −14.5 (±0.3) 
R394A-E395A −51.0 (±0.9) −15.5 (±0.3) 
R394A-Y485A −27.4 (±0.9) −8.3 (±0.3) 
E395A-Y485A −50.5 (±1.0) −15.3 (±0.3) 
E395A-V476A −78.8 (±1.4) −23.9 (±0.4) 
V476A-Y485A −61.4 (±1.6) −18.6 (±0.5) 
R394A-E395A-Y485A −40.0 (±1.9) −12.1 (±0.6) 
E395A-V476A-Y485A −66.6 (±0.6) −20.2 (±0.2) 

Gating currents for the mutants were measured either on a COVC or a TEV clamp set-up (bold). The VM of the normalized Q-V curve, for all of the mutants (averaged from n oocytes), along with its SEM (δVM) are reported for each mutant. ΔGnet was evaluated as QmaxFVM and its standard error as QmaxFδVM. For all mutants, a Qmax of 13.2 electronic charges was used for ΔGnet calculations.

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