Figure 4.

Binding of ¹²⁵I-ChTX to either α or α+β subunits of the maxi-K channel. Membranes prepared from COS-1 cells transiently transfected with either α (•) or α+β subunits (◊) of the maxi-K channel were incubated with increasing concentrations of ¹²⁵I-ChTX in a medium consisting of 10 mM NaCl, 20 mM Tris·HCl (pH 7.4), 0.1% BSA, 0.1% digitonin, and 5 μM paxilline, until equilibrium was achieved. Nonspecific binding was determined in the presence of 10 nM ChTX. Specific binding data are presented relative to the maximum receptor occupancy.