α‐Bungarotoxin Binding in House Fly Heads and Torpedo Electroplax

Abstract

House fly heads contain a site that binds alpha-bungarotoxin with high affinity. It is present at about 23 pmol/g of heads and binds alpha-bungarotoxin (labeled with [3H]pyridoxamine phosphate) reversibly with a Kd of 6 nM. The effects of 48 drugs have been compared on the alpha-bungarotoxin binding sites of house fly and Torpedo. The pharmacology of the house fly sites is similar to that previously reported for neuronal alpha-bungarotoxin binding sites in both vertebrates and invertebrates and is distinguishable from that of the classic nicotinic neuromuscular acetylcholine receptor, as exemplified by that of Torpedo electroplax. Differences between the house fly site and Torpedo include higher affinities of the Torpedo receptor for decamethonium, hexamethonium, carbamylcholine, and acetyl-beta-methylcholine, but lower affinities for nicotine, atropine, and dihydro-beta-erythroidine.

Quinuclidinyl Benzilate Binding in House Fly Heads and Rat Brain

“…The main difference between the pharmacology of house fly QNB binding and that of the established vertebrate muscarinic receptor is the lower effectiveness of drugs not classically considered muscarinic on the house fly site. This is in contrast with the result with a-BGT binding to house fly (and rat) brain where there are clear differences between the sensitivity of classic nicotinic receptors and the sensitivity of those sites to several nicotinic drugs (Morley et al, 1979;Jones et al, 1981).…”

“…a-Bungarotoxin (a-BGT) at M was completely ineffective. This clearly distinguishes the house fly head QNB binding site from the a-BGT binding site that is present in the same preparation (Jones et al, 1981). The ineffectiveness of these drugs and others such as choline, ouabain, and DFP are signs of the specificity of these sites.…”

Drosophila nicotinic acetylcholine receptor subunits and their native interactions with insecticidal peptide toxins

“…Translating our neurotoxin binding results to other target species, there are several studies showing that nAChRs are sensitive to α-Btx in other insects, including the cockroach Periplaneta americana , the moth Manduca sexta and the housefly Musca domestica ( Salgado and Saar, 2004 ; Eastham et al, 1998 ; Jones et al, 1981 ). The exact α-Btx binding mechanism in these organisms is unknown or under investigation ( Salgado, 2021 ).…”

α-Bungarotoxin Blocks Excitatory Synaptic Transmission Between Cercal Sensory Neurones and Giant Interneurone 2 of the Cockroach,Periplaneta Americana

“…A specific, saturable 125 1-a-bungarotoxin binding component, with the pharmacological properties of an acetylcholine receptor has been described in membrane extracts of the following insect preparations: fly heads of Drosophila melanogaster (Schmidt-Nielsen et al 1977;Hall, 1980;Dudai & Amsterdam, 1977;Dudai, 1977Dudai, , 1978Dudai, , 1980Rudloff, Jimenez & Bartels, 1980) andMusca domestica (Dudai, 1977;Harris et al 1979;Cattell, Harris & Donnellan, 1980;Jones, Sudershan & O'Brien, 1981), brain tissue of the moth Manduca sexta (Sanes, Prescott & Hildebrand, 1977;Hildebrand, 1980), cerebral ganglia of the locust Locusta migratoria (Breer, 1981) and in abdominal nerve cords of the cockroach Periplaneta americana (Gepner, Hall & Sattelle, 1978). These preparations have a high concentration of a-bungarotoxin binding sites.…”