Table 1.

Binding of ¹²⁵I-ChTX to α and α+β membranes

Membrane	Kd, pM	k−1, s−1	k1, M−1·s−1
α	45.14 ± 5.92 (n = 4)	0.0029 (n = 3)	5.5 × 107 (n = 3)
α+β	0.84 ± 0.11 (n = 5)	0.0004 (n = 5)	2.6 × 108 (n = 3)
α/α+β	53.7	7.3	0.21

The equilibrium dissociation constant (K_d) and the rate constants of association (k₁) and dissociation (k₋₁) for ¹²⁵I-ChTX binding to membranes derived from COS-1 cells transiently transfected with either α or α+β subunits of the maxi-K channel are presented. These values are the average of several different experiments.