Rockefeller University Press

Table I

Inactivation Properties of Wild-Type and Mutant Kv3.4 K⁺ Channels

	k_i	ΔG_i	ΔΔG_i	k_r	ΔG_r	ΔΔG_r	V_0.5	Slope	I_NI
	s⁻¹	kcal/mol	kcal/mol	s⁻¹	kcal/mol	kcal/mol	mV	mV/e-fold
WT	111.5 ± 21	14.57	—	2.4 ± 1.3	16.89	—	−32.5 ± 4.3	−4.8 ± 0.3	0.02 ± 0.02
	(33)			(23)			(30)
S8D	18.4 ± 2.3	15.62	1.07	6.9 ± 0.5	16.19	0.65	−22.2 ± 0.8	−5 ± 0.2	0.1 ± 0.006
	(4)			(4)			(4)
S9D	35.6 ± 4.6	15.22	0.68	2.7 ± 0.2	16.75	0.1	−24.6 ± 2.1	−5.6 ± 0.3	0.02 ± 0.01
	(10)			(7)			(7)
S15D	82.7 ± 2.8	14.73	0.18	4.4 ± 0.2	16.46	0.38	−31.6 ± 3.1	−4.8 ± 0.1	0.02 ± 0.005
	(4)			(5)			(4)
S21D	115.1 ± 9	14.54	0.01	2.5 ± 0.1	16.79	0.06	−31.6 ± 2	−4.7 ± 0.2	0.03 ± 0.02
	(7)			(7)			(7)
S[8,9]D	2.0 ± 0.4	16.92	2.37	13.8 ± 3.2	15.79	1.06	ND	ND	ND
	(6)			(4)			(5)
S[8,15]D	8.4 ± 0.6	16.08	1.53	15.2 ± 0.5	15.73	1.12	−15 ± 1.1	−5.8 ± 0.2	0.29 ± 0.02
	(4)			(4)			(4)
S[9,15]D	11.2 ± 0.3	15.91	1.36	6.23 ± 0.5	16.25	0.59	−13 ± 1.4	−5.6 ± 0.3	0.13 ± 0.003
	(3)			(4)			(4)
S[8,21]D	18.2 ± 0.5	15.81	1.26	11.5 ± 1.8	15.89	0.95	−18.4 ± 2	−5.3 ± 0.2	0.18 ± 0.02
	(4)			(4)			(4)
S[9,21]D	22.8 ± 1	15.49	0.94	4.3 ± 0.3	16.47	0.38	−20.3 ± 0.9	−5.2 ± 0.1	0.04 ± 0.003
	(4)			(3)			(3)
S[15,21]D	60.3 ± 5	14.92	0.37	6.6 ± 0.6	16.22	0.62	−24.3 ± 1.4	−4.8 ± 0.2	0.03 ± 0.007
	(9)			(4)			(8)
S[8,9,15]D	ND	ND	ND	ND	ND	ND	ND	ND	ND
	(5)			(5)			(5)
S[8,9,21]D	0.4 ± 0.1	17.9	3.35	ND	ND	ND	ND	ND	ND
	(5)			(6)			(6)
S[8,15,21]D	2.6 ± 0.2	16.77	2.22	16.1 ± 2.8	15.69	1.15	ND	ND	ND
	(4)			(3)			(5)
S[9,15,21]D	6.5 ± 0.4	16.22	1.68	8.2 ± 0.5	16.1	0.75	ND	ND	ND
	(4)			(4)			(4)
S[8,9,15,21]D	0.8 ± 0.2	17.44	2.89	ND	ND	ND	ND	ND	ND
	(3)			(4)			(7)
S8N	84.3 ± 4.1	14.72	0.16	4.9 ± 0.3	16.39	0.5	−28.7 ± 0.8	−5.1 ± 0.2	0.01 ± 0.005
	(4)			(4)			(4)
S8E	17.4 ± 0.9	15.65	1.09	10.2 ± 0.5	15.97	0.93	−13.3 ± 1.2	−6.7 ± 0.1	0.1 ± 0.01
	(4)			(4)			(3)

	k_i	ΔG_i	ΔΔG_i	k_r	ΔG_r	ΔΔG_r	V_0.5	Slope	I_NI
	s⁻¹	kcal/mol	kcal/mol	s⁻¹	kcal/mol	kcal/mol	mV	mV/e-fold
WT	111.5 ± 21	14.57	—	2.4 ± 1.3	16.89	—	−32.5 ± 4.3	−4.8 ± 0.3	0.02 ± 0.02
	(33)			(23)			(30)
S8D	18.4 ± 2.3	15.62	1.07	6.9 ± 0.5	16.19	0.65	−22.2 ± 0.8	−5 ± 0.2	0.1 ± 0.006
	(4)			(4)			(4)
S9D	35.6 ± 4.6	15.22	0.68	2.7 ± 0.2	16.75	0.1	−24.6 ± 2.1	−5.6 ± 0.3	0.02 ± 0.01
	(10)			(7)			(7)
S15D	82.7 ± 2.8	14.73	0.18	4.4 ± 0.2	16.46	0.38	−31.6 ± 3.1	−4.8 ± 0.1	0.02 ± 0.005
	(4)			(5)			(4)
S21D	115.1 ± 9	14.54	0.01	2.5 ± 0.1	16.79	0.06	−31.6 ± 2	−4.7 ± 0.2	0.03 ± 0.02
	(7)			(7)			(7)
S[8,9]D	2.0 ± 0.4	16.92	2.37	13.8 ± 3.2	15.79	1.06	ND	ND	ND
	(6)			(4)			(5)
S[8,15]D	8.4 ± 0.6	16.08	1.53	15.2 ± 0.5	15.73	1.12	−15 ± 1.1	−5.8 ± 0.2	0.29 ± 0.02
	(4)			(4)			(4)
S[9,15]D	11.2 ± 0.3	15.91	1.36	6.23 ± 0.5	16.25	0.59	−13 ± 1.4	−5.6 ± 0.3	0.13 ± 0.003
	(3)			(4)			(4)
S[8,21]D	18.2 ± 0.5	15.81	1.26	11.5 ± 1.8	15.89	0.95	−18.4 ± 2	−5.3 ± 0.2	0.18 ± 0.02
	(4)			(4)			(4)
S[9,21]D	22.8 ± 1	15.49	0.94	4.3 ± 0.3	16.47	0.38	−20.3 ± 0.9	−5.2 ± 0.1	0.04 ± 0.003
	(4)			(3)			(3)
S[15,21]D	60.3 ± 5	14.92	0.37	6.6 ± 0.6	16.22	0.62	−24.3 ± 1.4	−4.8 ± 0.2	0.03 ± 0.007
	(9)			(4)			(8)
S[8,9,15]D	ND	ND	ND	ND	ND	ND	ND	ND	ND
	(5)			(5)			(5)
S[8,9,21]D	0.4 ± 0.1	17.9	3.35	ND	ND	ND	ND	ND	ND
	(5)			(6)			(6)
S[8,15,21]D	2.6 ± 0.2	16.77	2.22	16.1 ± 2.8	15.69	1.15	ND	ND	ND
	(4)			(3)			(5)
S[9,15,21]D	6.5 ± 0.4	16.22	1.68	8.2 ± 0.5	16.1	0.75	ND	ND	ND
	(4)			(4)			(4)
S[8,9,15,21]D	0.8 ± 0.2	17.44	2.89	ND	ND	ND	ND	ND	ND
	(3)			(4)			(7)
S8N	84.3 ± 4.1	14.72	0.16	4.9 ± 0.3	16.39	0.5	−28.7 ± 0.8	−5.1 ± 0.2	0.01 ± 0.005
	(4)			(4)			(4)
S8E	17.4 ± 0.9	15.65	1.09	10.2 ± 0.5	15.97	0.93	−13.3 ± 1.2	−6.7 ± 0.1	0.1 ± 0.01
	(4)			(4)			(3)

The rate constants of inactivation (k_i) and recovery from inactivation (k_r) and the associated free energy changes (ΔG_i, ΔΔG_i, ΔG_r, and ΔΔG_r) were calculated as described under Experimental Procedures. The best-fit parameters of the prepulse inactivation curve (V_0.5, Slope, and I_NI) were obtained assuming a Boltzmann distribution. V_0.5 and I_NI represent the midpoint potential and the noninactivating fraction, respectively. The values were expressed as mean ± SD. The number of oocytes examined is indicated in parenthesis. ND indicates that the experiments were not analyzed quantitatively as explained in the text and legends of Figs. 5–7.

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