Use of Toxin Binding to Purify a Channel Protein a-Bungarotoxin is a powerful neurotoxin found in the venom of a poisonous snake (Bungarus multicinctus). It binds with high specificity to the nicotinic acetylcholine receptor (AChR) protein and prevents the ion channel from opening. This interaction was used to purify AChR from the electric organ of torpedo fish. (a) Outline a strategy for using a-bungarotoxin covalently bound to chromatography beads to purify the ACHR protein. (Hint: See Fig. 3-17c.) (b) Outline a strategy for the use of [251]a-bungarotoxin to purify the ACHR protein.