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. 2012 Apr;139(4):295–304. doi: 10.1085/jgp.201110725

TABLE 1.

Inhibition constant IC50 and transmembrane electric distance for wt-Kcv and various Leu70 mutants

Residue type and mutant I (−60 mV) IC50 (−60 mV) δ (−V) I (60 mV) IC50 (60 mV) δ (+V)
pA mM pA mM
Aromatic
L70Y −15.7 ± 1.2 0.74 ± 0.09 0.06 16.3 ± 1.1 1.9 ± 0.2 0.25
L70F −17.6 ± 0.8 0.86 ± 0.07 0.09 15.9 ± 1.2 2.0 ± 0.2 0.26
L70H −6.51 ± 0.42 3.3 ± 0.5 0.00 12.6 ± 1.5 3.6 ± 0.7 0.16
L70W −15.0 ± 0.9 8.6 ± 0.7 0.09 14.1 ± 0.7 22 ± 3 0.27
Nonpolar
wt (L70) −5.43 ± 1.3 0.098 ± 0.02 0.12 12.0 ± 1.1 0.41 ± 0.03 0.29
L70M −10.4 ± 0.6 6.8 ± 1.1 0.15 11.4 ± 0.6 19 ± 2 0.22
L70I −9.81 ± 1.10 9.8 ± 0.7 0.06 13.7 ± 0.4 18 ± 2 0.21
L70V −12.5 ± 0.4 17 ± 3 0.09 15.1 ± 0.9 31 ± 4 0.23
L70A −11.3 ± 1.2 45 ± 5 0.08 13.9 ± 1.1 72 ± 18 0.22
Polar
L70C −16.4 ± 0.6 4.9 ± 0.2 0.06 14.8 ± 0.2 12 ± 2 0.23
L70S −13.4 ± 1.2 14 ± 2 0.00 15.8 ± 1.0 21 ± 4 0.21
L70T −13.3 ± 0.8 23 ± 4 0.12 17.6 ± 0.7 41 ± 7 0.25
Charged
L70Ka ND ND ND 4.48 ± 0.28 NS ND
L70E −11.5 ± 0.6 79 ± 11 ND 12.8 ± 1.1 NS ND

The relative electrical distance δ was calculated from the voltage dependence of IC50 according to the Woodhull equation I/I0(V) = I/I0(0)exp(−zδFV/RT), where z = 1 is the valence of TEA, F is the Faraday constant, R is the gas constant, and T is the temperature (in K).

a

The negative current of L70K was not observed; thus, the TEA sensitivity cannot be determined.