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TABLE I

Voltage-dependent Gating and Rectification of Cysteine Mutants




Vo

z

Pmin

Rectification

n
WTa  −99 ± 0.8 0.90 ± 0.02 0.076 ± 0.005 1.00 ± 0.004 68 
Q114C  −95 ± 2.2 0.87 ± 0.03 0.063 ± 0.013 0.99 ± 0.007 16 
S117C  −98 ± 3.9 0.93 ± 0.02 0.073 ± 0.013 0.98 ± 0.011 
P118C  −93 ± 2.5 0.91 ± 0.01 0.056 ± 0.012 0.98 ± 0.012 
Q119C  −106 ± 1.7 0.86 ± 0.02 0.048 ± 0.037 0.98 ± 0.015 
A120C  −86 ± 1.9 0.94 ± 0.02 0.041 ± 0.007 0.98 ± 0.009 13 
V121C  −91 ± 1.3 0.91 ± 0.02 0.081 ± 0.013 0.99 ± 0.017 13 
G122C  −94 ± 1.6 0.83 ± 0.02 0.044 ± 0.011 0.85 ± 0.008 17 
S123Cb ND ND ND ND 
P126C  −80 ± 2.2 0.73 ± 0.02 0.035 ± 0.011 0.84 ± 0.020 12 
L128C  −94 ± 1.5 0.94 ± 0.11 0.122 ± 0.046 1.12 ± 0.006 
V136C  −97 ± 2.0 0.90 ± 0.02 0.069 ± 0.017 0.98 ± 0.012 
H138C  −90 ± 2.5 0.93 ± 0.04 0.058 ± 0.013 1.02 ± 0.010 
T142C  −90 ± 2.3 0.83 ± 0.04 0.052 ± 0.015 0.98 ± 0.007 
R144C  −91 ± 1.1 0.89 ± 0.02 0.058 ± 0.008 1.01 ± 0.007 10 
K149Cb  −28 ± 0.8 0.98 ± 0.01 0.042 ± 0.008 0.87 ± 0.007 19 
H171C  −101 ± 1.5 0.86 ± 0.03 0.069 ± 0.016 1.02 ± 0.009 12 
N304C  −91 ± 3.4 0.80 ± 0.03 0.051 ± 0.025 0.99 ± 0.010 
R305C  −92 ± 1.9 0.86 ± 0.05 0.055 ± 0.027 0.98 ± 0.024 
Q306C  −95 ± 1.6 0.94 ± 0.04 0.067 ± 0.022 0.98 ± 0.005 
I307C  −94 ± 1.8 0.88 ± 0.03 0.045 ± 0.017 0.98 ± 0.008 13 
I308C  −94 ± 1.0 0.95 ± 0.01 0.091 ± 0.006 1.00 ± 0.005 60 
V309C  −90 ± 1.3 0.93 ± 0.03 0.066 ± 0.011 1.01 ± 0.009 12 
F310C  −95 ± 1.2 0.89 ± 0.03 0.107 ± 0.030 0.98 ± 0.017 
M311C  −92 ± 0.9 0.94 ± 0.02 0.085 ± 0.017 0.99 ± 0.005 19 
R312C  −95 ± 1.5 0.89 ± 0.01 0.072 ± 0.006 0.93 ± 0.009 26 
K313C  −92 ± 1.0 0.95 ± 0.02 0.076 ± 0.011 1.01 ± 0.005 12 
K314C  −94 ± 0.7 0.91 ± 0.07 0.044 ± 0.023 1.02 ± 0.021 
N315C  −85 ± 2.9 0.87 ± 0.02 0.049 ± 0.006 0.98 ± 0.011 
F316C  −89 ± 1.0 0.94 ± 0.02 0.063 ± 0.008 0.98 ± 0.010 10 
V409C  −90 ± 0.7 0.93 ± 0.03 0.096 ± 0.011 0.96 ± 0.008 
T410C  −96 ± 0.9 0.75 ± 0.05 0.067 ± 0.019 0.88 ± 0.018 
P412C  −86 ± 1.4 0.83 ± 0.03 0.043 ± 0.012 0.90 ± 0.023 
Y512C  −98 ± 2.1 0.85 ± 0.02 0.000 ± 0.000 0.89 ± 0.007 12 
D513C  −92 ± 1.2 0.71 ± 0.01 0.032 ± 0.009 1.00 ± 0.010 35 
S514C  −98 ± 3.1 0.83 ± 0.02 0.064 ± 0.009 1.00 ± 0.010 10 
I515C  −87 ± 0.8 0.97 ± 0.01 0.029 ± 0.003 0.95 ± 0.006 93 
I516C  −101 ± 2.3 0.88 ± 0.05 0.134 ± 0.020 0.91 ± 0.017 13 
Q517C  −92 ± 1.1 0.94 ± 0.01 0.063 ± 0.008 1.02 ± 0.010 
I518C  −91 ± 2.0 0.97 ± 0.03 0.072 ± 0.009 1.02 ± 0.005 10 
K519Cb  −114 ± 1.9 0.65 ± 0.01 0.241 ± 0.017 0.61 ± 0.006 56 
K520C  −104 ± 1.5 0.84 ± 0.05 0.077 ± 0.039 1.00 ± 0.019 
L521Cc      
P522C  −94 ± 1.6 0.83 ± 0.02 0.115 ± 0.014 0.98 ± 0.005 26 
Y523C  −95 ± 1.7 0.92 ± 0.02 0.124 ± 0.012 0.97 ± 0.006 24 
L524C  −98 ± 1.4 0.88 ± 0.02 0.058 ± 0.009 0.97 ± 0.004 18 
P525C  −98 ± 1.1 0.90 ± 0.03 0.110 ± 0.010 0.97 ± 0.007 
E526C  −104 ± 1.5 0.84 ± 0.03 0.050 ± 0.021 0.98 ± 0.011 
L527C  −107 ± 2.0 0.87 ± 0.01 0.057 ± 0.017 1.01 ± 0.008 
S528C  −107 ± 2.1 0.88 ± 0.04 0.045 ± 0.021 1.01 ± 0.011 
W529C  −96 ± 1.7 0.85 ± 0.04 0.047 ± 0.019 0.98 ± 0.009 
S530C  −105 ± 2.2 0.85 ± 0.05 0.044 ± 0.028 1.00 ± 0.006 
S531C  −106 ± 1.7 0.92 ± 0.01 0.074 ± 0.006 1.00 ± 0.001 



Vo

z

Pmin

Rectification

n
WTa  −99 ± 0.8 0.90 ± 0.02 0.076 ± 0.005 1.00 ± 0.004 68 
Q114C  −95 ± 2.2 0.87 ± 0.03 0.063 ± 0.013 0.99 ± 0.007 16 
S117C  −98 ± 3.9 0.93 ± 0.02 0.073 ± 0.013 0.98 ± 0.011 
P118C  −93 ± 2.5 0.91 ± 0.01 0.056 ± 0.012 0.98 ± 0.012 
Q119C  −106 ± 1.7 0.86 ± 0.02 0.048 ± 0.037 0.98 ± 0.015 
A120C  −86 ± 1.9 0.94 ± 0.02 0.041 ± 0.007 0.98 ± 0.009 13 
V121C  −91 ± 1.3 0.91 ± 0.02 0.081 ± 0.013 0.99 ± 0.017 13 
G122C  −94 ± 1.6 0.83 ± 0.02 0.044 ± 0.011 0.85 ± 0.008 17 
S123Cb ND ND ND ND 
P126C  −80 ± 2.2 0.73 ± 0.02 0.035 ± 0.011 0.84 ± 0.020 12 
L128C  −94 ± 1.5 0.94 ± 0.11 0.122 ± 0.046 1.12 ± 0.006 
V136C  −97 ± 2.0 0.90 ± 0.02 0.069 ± 0.017 0.98 ± 0.012 
H138C  −90 ± 2.5 0.93 ± 0.04 0.058 ± 0.013 1.02 ± 0.010 
T142C  −90 ± 2.3 0.83 ± 0.04 0.052 ± 0.015 0.98 ± 0.007 
R144C  −91 ± 1.1 0.89 ± 0.02 0.058 ± 0.008 1.01 ± 0.007 10 
K149Cb  −28 ± 0.8 0.98 ± 0.01 0.042 ± 0.008 0.87 ± 0.007 19 
H171C  −101 ± 1.5 0.86 ± 0.03 0.069 ± 0.016 1.02 ± 0.009 12 
N304C  −91 ± 3.4 0.80 ± 0.03 0.051 ± 0.025 0.99 ± 0.010 
R305C  −92 ± 1.9 0.86 ± 0.05 0.055 ± 0.027 0.98 ± 0.024 
Q306C  −95 ± 1.6 0.94 ± 0.04 0.067 ± 0.022 0.98 ± 0.005 
I307C  −94 ± 1.8 0.88 ± 0.03 0.045 ± 0.017 0.98 ± 0.008 13 
I308C  −94 ± 1.0 0.95 ± 0.01 0.091 ± 0.006 1.00 ± 0.005 60 
V309C  −90 ± 1.3 0.93 ± 0.03 0.066 ± 0.011 1.01 ± 0.009 12 
F310C  −95 ± 1.2 0.89 ± 0.03 0.107 ± 0.030 0.98 ± 0.017 
M311C  −92 ± 0.9 0.94 ± 0.02 0.085 ± 0.017 0.99 ± 0.005 19 
R312C  −95 ± 1.5 0.89 ± 0.01 0.072 ± 0.006 0.93 ± 0.009 26 
K313C  −92 ± 1.0 0.95 ± 0.02 0.076 ± 0.011 1.01 ± 0.005 12 
K314C  −94 ± 0.7 0.91 ± 0.07 0.044 ± 0.023 1.02 ± 0.021 
N315C  −85 ± 2.9 0.87 ± 0.02 0.049 ± 0.006 0.98 ± 0.011 
F316C  −89 ± 1.0 0.94 ± 0.02 0.063 ± 0.008 0.98 ± 0.010 10 
V409C  −90 ± 0.7 0.93 ± 0.03 0.096 ± 0.011 0.96 ± 0.008 
T410C  −96 ± 0.9 0.75 ± 0.05 0.067 ± 0.019 0.88 ± 0.018 
P412C  −86 ± 1.4 0.83 ± 0.03 0.043 ± 0.012 0.90 ± 0.023 
Y512C  −98 ± 2.1 0.85 ± 0.02 0.000 ± 0.000 0.89 ± 0.007 12 
D513C  −92 ± 1.2 0.71 ± 0.01 0.032 ± 0.009 1.00 ± 0.010 35 
S514C  −98 ± 3.1 0.83 ± 0.02 0.064 ± 0.009 1.00 ± 0.010 10 
I515C  −87 ± 0.8 0.97 ± 0.01 0.029 ± 0.003 0.95 ± 0.006 93 
I516C  −101 ± 2.3 0.88 ± 0.05 0.134 ± 0.020 0.91 ± 0.017 13 
Q517C  −92 ± 1.1 0.94 ± 0.01 0.063 ± 0.008 1.02 ± 0.010 
I518C  −91 ± 2.0 0.97 ± 0.03 0.072 ± 0.009 1.02 ± 0.005 10 
K519Cb  −114 ± 1.9 0.65 ± 0.01 0.241 ± 0.017 0.61 ± 0.006 56 
K520C  −104 ± 1.5 0.84 ± 0.05 0.077 ± 0.039 1.00 ± 0.019 
L521Cc      
P522C  −94 ± 1.6 0.83 ± 0.02 0.115 ± 0.014 0.98 ± 0.005 26 
Y523C  −95 ± 1.7 0.92 ± 0.02 0.124 ± 0.012 0.97 ± 0.006 24 
L524C  −98 ± 1.4 0.88 ± 0.02 0.058 ± 0.009 0.97 ± 0.004 18 
P525C  −98 ± 1.1 0.90 ± 0.03 0.110 ± 0.010 0.97 ± 0.007 
E526C  −104 ± 1.5 0.84 ± 0.03 0.050 ± 0.021 0.98 ± 0.011 
L527C  −107 ± 2.0 0.87 ± 0.01 0.057 ± 0.017 1.01 ± 0.008 
S528C  −107 ± 2.1 0.88 ± 0.04 0.045 ± 0.021 1.01 ± 0.011 
W529C  −96 ± 1.7 0.85 ± 0.04 0.047 ± 0.019 0.98 ± 0.009 
S530C  −105 ± 2.2 0.85 ± 0.05 0.044 ± 0.028 1.00 ± 0.006 
S531C  −106 ± 1.7 0.92 ± 0.01 0.074 ± 0.006 1.00 ± 0.001 
a

WT refers to C212S, the background for all cysteine point mutants.

b

Mutants with Vo shifted >20 mV or rectification changed by >20% from wild type.

c

Mutants for which no current could be detected.

Effects of cysteine mutagenesis. Voltage-dependent gating parameters for wild type and cysteine point mutants: midpoint of the voltage–activation curve (Vo), effective gating charge (z), and minimum open probability (Pmin). Rectification is quantified as described in materials and methods and normalized to wild type, which is slightly inwardly rectifying. Values greater than one indicate inward rectification with respect to wild type; values less than one indicate outward rectification with respect to wild type. Experiments were carried out in slightly asymmetric solution conditions, such that the expected rectification is 1.04 according to the Goldman-Hodgkin-Katz current equation.

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