Interaction with chick myotube cholinergic receptors of an alpha-neurotoxin isolated from venom of the banded krait (Bungarus fasciatus).
A postsynaptic acting short chain alpha-toxin, B.f. III, was isolated from venom of the banded krait (Bungarus fasciatus) using ion-exchange chromatography. The toxin, a basic protein (pI = 10) has an apparent molecular weight of 6,500 as determined by SDS-polyacrylamide gel electrophoresis. It shares immunological determinants with alpha-bungarotoxin, as it cross-reacted with antibodies raised in rabbits against alpha-bungarotoxin. B.f. III inhibits binding of 125I-alpha-bungarotoxin to cultured chick myotubes with an IC50 of 3 X 10(-10) M. The rate of association with chick myotube nAChR was 3 times faster than that of alpha-bungarotoxin, and binding was slowly reversible. The toxin is a less potent antagonist than alpha-bungarotoxin; in ion flux experiments, measuring influx of 86Rb in chick myotubes, B.f. III inhibited carbachol-induced influx of 86Rb (IC50 = 5 X 10(-9) M) at concentrations higher than those needed for alpha-bungarotoxin (IC50 = 6 X 10(-10) M).
D000818:Animals; D001667:Binding, Competitive; D002038:Bungarotoxins / Q000378:metabolism; D002217:Carbachol / Q000037:antagonists & inhibitors; D002642:Chick Embryo; D046508:Culture Techniques; D004546:Elapid Venoms / Q000032:analysis*; D000939:Epitopes; D008970:Molecular Weight; D009132:Muscles / Q000378:metabolism*; D009498:Neurotoxins / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D011950:Receptors, Cholinergic / Q000378:metabolism*; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor
D002038:Bungarotoxins; D004546:Elapid Venoms; D000939:Epitopes; D009498:Neurotoxins; D011950:Receptors, Cholinergic; D011978:Receptors, Nicotinic; D064569:alpha7 Nicotinic Acetylcholine Receptor; D002217:Carbachol