α-bungarotoxin, has been used extensively to characterize
vertebrate nAChRs because it selectively binds to certain
populations of vertebrate receptors. It is one of a family of
small neurotoxic proteins (MW ～ 8,000 Da) isolated from
the venom of elapid snakes (cobras and their relatives).
α-Bungarotoxin also binds to certain insect nAChRs (8,9),
although a separate α-bungarotoxin–insensitive class of
nAChR has been found in some species (9). It binds
very tightly to the receptor and competitively blocks
the binding of acetylcholine; consequently, radiolabeled
α-bungarotoxin has been used to design competitive binding
assays to measure the in vitro potencies of competitive
ligands such as the neonicotinoids.
