TABLE I

Substitution Scan of the C-terminal Part of S6

hKv1.5
V
P
V
I
V
S
N
F
N
Y
F
Y
H
R
E
T
D
  I  I  I  I  I  I  I  I  
position  513  515  517  519  521  523  525  527  
  (475)  (477)  (479)  (481)  (483)  (485)  (487)  (489)  
 Activation        Deactivation   Inactivation      
 V1/2 (mV)
 		  k (mV)
 		 τa (ms)
 		  τd (ms)
 		  V1/2,i (mV)
 		  ki (mV)
 		 n
 
hKv1.5 −14.3 ± 1.0   5.8 ± 0.2  3.5 ± 0.2   24.9 ± 2.5   −23.2 ± 1.3   3.9 ± 0.1  8 
I515G no current                5 
V516G no current                9 
S517G 0.3 ± 1   6.4 ± 0.4  5.1 ± 0.7   31.9 ± 3.5   −8.3 ± 1.3   4.6 ± 0.3  6 
N518G no current                8 
F519G no current                14 
N520G 2.8 ± 1.7   6.7 ± 0.3  6.9 ± 0.5   21.4 ± 3.9   −6.6 ± 1.4   4.6 ± 0.2  7 
Y521G >28   >32  13.0 ± 0.9   18.6 ± 3.1   −18.7 ± 1.5   4.4 ± 0.4  4 
F522G no current                9 
Y523G no current                16 
H524G −9.8 ± 2   6.9 ± 0.4  6.5 ± 1.0   23.5 ± 1.5   −18.5 ± 2.7   5.1 ± 0.3  5 
R525G −5.9 ± 1.7   6.9 ± 0.5  6.3 ± 0.6   11.8 ± 1.2   −15.7 ± 1.3   4.0 ± 0.3  5 
E526G −0.7 ± 1.5   5.7 ± 0.3  3.3 ± 0.2   11.1 ± 0.8   −7.8 ± 1.4   4.6 ± 0.3  7 
T527G 5.5 ± 1.7   6.4 ± 0.4  4.9 ± 0.5   12.7 ± 0.9   0.8 ± 2.2   5.1 ± 0.5  6 
I515A no current                6 
V516A −7.3 ± 1.8   6.0 ± 0.3  4.0 ± 0.6   3.6 ± 0.3   −11.6 ± 1.8   3.8 ± 0.2  7 
S517A −1.1 ± 1.5   6.7 ± 0.2  5.3 ± 1.0   26.0 ± 3.2   −11.6 ± 1.2   4.9 ± 0.1  6 
N518A no current                9 
F519A no current                8 
N520A −5.2 ± 1.4   6.9 ± 0.3  4.3 ± 0.3   38.4 ± 0.9   −15.3 ± 0.5   4.8 ± 0.3  6 
Y521A −16.6 ± 1.3   5.4 ± 0.3  3.3 ± 0.2   5.0 ± 0.4   −20.4 ± 1.1   3.9 ± 0.2  5 
F522A no current                11 
Y523A no current                16 
H524A −16.1 ± 1.6   6.7 ± 0.4  5.6 ± 0.4   33.7 ± 5.2   −25.2 ± 1.9   4.3 ± 0.2  7 
R525A −14.0 ± 1.3   6.1 ± 0.4  5.1 ± 0.7   31.2 ± 3.8   −23.9 ± 1.3   4.1 ± 0.3  6 
E526A −15.0 ± 1.2   6.7 ± 0.5  4.6 ± 0.5   18.7 ± 2.3   −23.1 ± 1.1   4.3 ± 0.1  8 
T527A −5.0 ± 2.2   6.6 ± 0.6  7.1 ± 1.5   21.4 ± 2.8   −11.8 ± 1.2   4.6 ± 0.4  5 
V516P no current                5 
S517P no current                7 
N520P no current                7 
Y521P no current                5 
F519L no current                5 
F522L −20.6 ± 3.2   5.2 ± 0.6  3.3 ± 0.3   32.8 ± 3.9   −28.1 ± 2.9   3.6 ± 0.1  5 
Y523L −22.8 ± 2.2   5.5 ± 0.5  3.6 ± 0.3   145 ± 18   −31.7 ± 0.9   3.7 ± 0.2  6 
hKv1.5
V
P
V
I
V
S
N
F
N
Y
F
Y
H
R
E
T
D
  I  I  I  I  I  I  I  I  
position  513  515  517  519  521  523  525  527  
  (475)  (477)  (479)  (481)  (483)  (485)  (487)  (489)  
 Activation        Deactivation   Inactivation      
 V1/2 (mV)
 		  k (mV)
 		 τa (ms)
 		  τd (ms)
 		  V1/2,i (mV)
 		  ki (mV)
 		 n
 
hKv1.5 −14.3 ± 1.0   5.8 ± 0.2  3.5 ± 0.2   24.9 ± 2.5   −23.2 ± 1.3   3.9 ± 0.1  8 
I515G no current                5 
V516G no current                9 
S517G 0.3 ± 1   6.4 ± 0.4  5.1 ± 0.7   31.9 ± 3.5   −8.3 ± 1.3   4.6 ± 0.3  6 
N518G no current                8 
F519G no current                14 
N520G 2.8 ± 1.7   6.7 ± 0.3  6.9 ± 0.5   21.4 ± 3.9   −6.6 ± 1.4   4.6 ± 0.2  7 
Y521G >28   >32  13.0 ± 0.9   18.6 ± 3.1   −18.7 ± 1.5   4.4 ± 0.4  4 
F522G no current                9 
Y523G no current                16 
H524G −9.8 ± 2   6.9 ± 0.4  6.5 ± 1.0   23.5 ± 1.5   −18.5 ± 2.7   5.1 ± 0.3  5 
R525G −5.9 ± 1.7   6.9 ± 0.5  6.3 ± 0.6   11.8 ± 1.2   −15.7 ± 1.3   4.0 ± 0.3  5 
E526G −0.7 ± 1.5   5.7 ± 0.3  3.3 ± 0.2   11.1 ± 0.8   −7.8 ± 1.4   4.6 ± 0.3  7 
T527G 5.5 ± 1.7   6.4 ± 0.4  4.9 ± 0.5   12.7 ± 0.9   0.8 ± 2.2   5.1 ± 0.5  6 
I515A no current                6 
V516A −7.3 ± 1.8   6.0 ± 0.3  4.0 ± 0.6   3.6 ± 0.3   −11.6 ± 1.8   3.8 ± 0.2  7 
S517A −1.1 ± 1.5   6.7 ± 0.2  5.3 ± 1.0   26.0 ± 3.2   −11.6 ± 1.2   4.9 ± 0.1  6 
N518A no current                9 
F519A no current                8 
N520A −5.2 ± 1.4   6.9 ± 0.3  4.3 ± 0.3   38.4 ± 0.9   −15.3 ± 0.5   4.8 ± 0.3  6 
Y521A −16.6 ± 1.3   5.4 ± 0.3  3.3 ± 0.2   5.0 ± 0.4   −20.4 ± 1.1   3.9 ± 0.2  5 
F522A no current                11 
Y523A no current                16 
H524A −16.1 ± 1.6   6.7 ± 0.4  5.6 ± 0.4   33.7 ± 5.2   −25.2 ± 1.9   4.3 ± 0.2  7 
R525A −14.0 ± 1.3   6.1 ± 0.4  5.1 ± 0.7   31.2 ± 3.8   −23.9 ± 1.3   4.1 ± 0.3  6 
E526A −15.0 ± 1.2   6.7 ± 0.5  4.6 ± 0.5   18.7 ± 2.3   −23.1 ± 1.1   4.3 ± 0.1  8 
T527A −5.0 ± 2.2   6.6 ± 0.6  7.1 ± 1.5   21.4 ± 2.8   −11.8 ± 1.2   4.6 ± 0.4  5 
V516P no current                5 
S517P no current                7 
N520P no current                7 
Y521P no current                5 
F519L no current                5 
F522L −20.6 ± 3.2   5.2 ± 0.6  3.3 ± 0.3   32.8 ± 3.9   −28.1 ± 2.9   3.6 ± 0.1  5 
Y523L −22.8 ± 2.2   5.5 ± 0.5  3.6 ± 0.3   145 ± 18   −31.7 ± 0.9   3.7 ± 0.2  6 

On top the sequence of the S6T region of hKv1.5. The mutations are represented with the residue numbering of hKv1.5. Midpoint of activation (V1/2) and slope factor of activation (k) were calculated as described in Materials and methods. The time constants of activation (τa) and deactivation (τd) were obtained at V1/2 +60 mV and V1/2 −40 mV, respectively. In the case of Y521G, the V1/2 was too positive and the slope too shallow to be determined by curve fitting, precluding an accurate estimate. For Y521G, the time constant of activation and deactivation was obtained at +80 mV and −30 mV. Midpoint of inactivation (V1/2,i) and slope factor (ki) were obtained from the reduction of current during a step to +50 mV after a 5-s prepulse to voltages between −80 and +20 mV.

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