Table 2.

Binding of conotoxins to purified nAChR subtypes

	Kd for 125I-epibatidine	Ki (CV) for α-conotoxin MII	Ki (CV) for α-conotoxin MII [H9A,L15A]	Ki (CV) for α-conotoxin PIA
α6β2* purified from superior colliculus	38 pm	3 nm (39%) and >10 μm	1.8 μm (57%)	37 nm (59%)
α3β2* purified from HEK cells	35 pm	55 nm (59%)a	>10 μm	>10 μm
α4β2* purified from cerebral cortex	33 pm	>10 μm	>10 μm	>10 μm
α3β4* purified from cerebellum	98 pm	>10 μm	>10 μm	>10 μm

^aThe K_i value of CntxMII was found to be 115 nm for α3β2* nAChRs immunopurified from rat superior colliculus (Gotti et al., 2005b).