CHARACTERIZATION OF AN α-BUNGAROTOXIN BINDING COMPONENT FROM DROSOPHILA MELANOGASTER

Abstract— We describe an α-bungarotoxin binding component from Dromphila melanoyaster that has the properties expected of an acetylcholine receptor. Toxin binding to a paniculate form of this component has been shown to be proportional to amount of extract, to be saturable and to be destroyed by heat. Localization studies using ¹²⁵I-α-bungarotoxin binding to frozen sections has shown toxin binding to be restricted to synaptic areas of the Drosophila CNS. We have also shown that this toxinbinding component can be treated with Triton X-100 without significantly altering its toxin-binding and pharmacological specificity. The ability of preincubation with cholinergic ligands to block labeled α-bungarotoxin binding to both particulate and detergent treated extracts has been studied. The nicotinic agents nicotine, d-tubocurarine, and acetylcholine are the most effective blocking agents. All of the muscarinic agents tested and the nicotinic agent decamethonium were less effective than acetylcholine in preventing α-bungarotoxin binding.