. 2004 Jul;124(1):71–81. doi: 10.1085/jgp.200409048

TABLE I.

Dependence of κ-PVIIA Binding Parameters to Shaker-Δ Channels on the Solution Composition

		Open channel block				Closed channel block
Extra	Intra	K^O(0)	v_s	k^O _on	k^O _off(0)	K^C	k^C _on	k^C _off
		nM	mV	μM⁻¹s⁻¹	s⁻¹	nM	μM⁻¹s⁻¹	s⁻¹
K⁺	K⁺	148 ± 52	41 ± 6	155 ± 61	21 ± 9	246 ± 69	1.9 ± 0.5	0.6 ± 0.3
							(*)	(*)
Rb⁺	Rb⁺	1023 ± 192	76 ± 10	119 ± 58	150 ± 26	241 ± 41	>>25	>>5
			(1.7 ± 0.3%) mV⁻¹				(**)	(**)
K⁺	Rb⁺	252 ± 21	32 ± 3	94 ± 48	18 ± 6	308 ± 35	2.7 ± 0.6	0.9 ± 0.1
				(V_P < 0)
Rb⁺	K⁺	231 ± 50	45 ± 6	104 ± 20	30 ± 10	139 ± 31
		(V_P > 0)	(V_P > 0)	(V_P > 0)	(V_P > 0)

Patch-clamp experiments performed in the outside-out configuration, number of experiments between 4 and 14, with 1–4 toxin applications for each experiment. The toxin concentrations used varied between 100 nM and 1 μM (K_ext/K_int: 100–400 nM; K_ext/Rb_int: 100–400 nM; Rb_ext/K_int: 100–500nM; Rb_ext/Rb_int: 300–1,000 nM). Open channel block parameters were pooled from data collected at V_P between −60 and +80 mV, if not otherwise stated. K^O(0) and vs are the mean values of the single exponential fit parameters obtained for each experiment. In symmetrical Rb, the weaker voltage dependence can also be described with a linear fit. Mean values (±SD) are reported, otherwise obtained (*) from fit of the τ as a function of [T] with τ =1/(k_off + k_on* [T]). For the symmetrical Rb case (**) a lower limit estimate is obtained from k_off = (1/τ)* (K^C/(K^C + [T])); k_on = (1/τ)/(K^C + [T]) when τ >> τ_d, where τ_d is the channel deactivation time.