Search for ligands of neuronal alpha-bungarotoxin receptors

Extracts of calf brain were analyzed for substances capable of blocking the binding of [125I]-alpha-bungarotoxin to chick brain membrane preparations, and shown to contain blocking activity that was insensitive to heating and trypsin. Fractionation on Sephadex G-25 yielded two components, one representing nonspecific inhibition by inorganic cations, the other identified as choline by co-chromatography experiments and analysis of the purified inhibitor using thin layer chromatography and mass spectrometry. These results support the notion that the alpha-bungarotoxin binding macromolecule in the central nervous system is an acetylcholine receptor.