J. Biol. Chem., Vol. 255, Issue 2, 526-533, 01, 1980
Binding properties of a neurotoxin from the venom of the green mamba, Dendroaspis viridis
J Patrick, WB Stallcup, M Zavanelli and P Ravdin
A toxin, alpha-mambatoxin, was purified from the venom of the green mamba
Dendroaspis viridis using the procedures of Shipolini et al. (Shipolini, R.
A., Bailey, G. S., Edwardson, J. A., and Banks, E. C. (1973) Eur. J.
Biochem. 40, 337-344). The purified toxin blocks agonist- induced
activation of acetylcholine receptors on muscle cells but, like
alpha-bungarotoxin, it does not affect agonist-induced activation of
receptors on a clonal sympathetic nerve cell line (PC12), an endothelial
cell line, cultured chick ciliary ganglion neurons, or frog cardiac
ganglion neurons. The toxin does block binding of alpha- bungarotoxin to
cultures of muscle and nerve, and iodinated alpha- mambatoxin binds to
cultures of muscle and nerve. The alpha-mambatoxin binding component on
muscle was identified as acetylcholine receptor on the basis of
sedimentation, immunoprecipitation, and rate of degradation. The
alpha-mambatoxin binding component on PC12 cells, like the
alpha-bungarotoxin binding component on these cells, is not recognized by
anti-acetylcholine receptor antisera which do recognize acetylcholine
receptor on these cells. The number of alpha-mambatoxin binding sites on
both nerve and muscle when assayed in situ is twice that of
alpha-bungarotoxin binding sites. However, when muscle cells are
solubilized in nonionic detergents and then labeled with toxins, the number
of alpha-mambatoxin binding sites is reduced and the two toxins bind in
equal molar amounts. Finally, unlike alpha-bungarotoxin, which dissociates
from complexes formed with nerve, alpha-mambatoxin forms complexes with
nerve which dissociate only very slowly if at all.
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