Interaction with chick myotube cholinergic receptors of an alpha-neurotoxin isolated from venom of the banded krait (Bungarus fasciatus)

Toxicon. 1986;24(7):713-9. doi: 10.1016/0041-0101(86)90034-6.

Abstract

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).

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding, Competitive
  • Bungarotoxins / metabolism
  • Carbachol / antagonists & inhibitors
  • Chick Embryo
  • Culture Techniques
  • Elapid Venoms / analysis*
  • Epitopes
  • Molecular Weight
  • Muscles / metabolism*
  • Neurotoxins / isolation & purification
  • Neurotoxins / metabolism*
  • Neurotoxins / pharmacology
  • Receptors, Cholinergic / metabolism*
  • Receptors, Nicotinic*
  • alpha7 Nicotinic Acetylcholine Receptor

Substances

  • Bungarotoxins
  • Elapid Venoms
  • Epitopes
  • Neurotoxins
  • Receptors, Cholinergic
  • Receptors, Nicotinic
  • alpha7 Nicotinic Acetylcholine Receptor
  • Carbachol