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Title
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Isolation and characterization of hainantoxin-IV, a novel antagonist of tetrodotoxin-sensitive sodium channels from the Chinese bird spider Selenocosmia hainana.
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Authors
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Z.Liu,
J.Dai,
Z.Chen,
W.Hu,
Y.Xiao,
S.Liang.
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Ref.
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Cell Mol Life Sci, 2003,
60,
972-978.
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PubMed id
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Abstract
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A neurotoxin, named hainantoxin-IV, was purified from the venom of the spider
Selenocosmia hainana. The amino acid sequence was determined by Edman
degradation, revealing it to be a 35-residue polypeptide amidated at its C
terminal and including three disulfide bridges: Cys2-Cys17, Cys9-Cys24, and
Cys16-Cys31 assigned by partial reduction and sequence analysis. Hainantoxin-IV
shares 80% sequence identity with huwentoxin-IV from the spider S. huwena, a
potent antagonist that acts at site 1 on tetrodotoxin-sensitive (TTX-S) sodium
channels, suggesting that hainantoxin-IV adopts an inhibitor cystine knot
structural motif like huwentoin-IV. Under whole-cell voltage-clamp conditions,
this toxin has no effect on tetrodotoxin-resistant voltage-gated sodium channels
in adult rat dorsal root ganglion neurons, while it blocks TTX-S sodium channels
in a manner similar to huwentoxin-IV, and the actions of both toxins on sodium
currents are very similar to that of tetrodotoxin. Thus, they define a new
family of spider toxins affecting sodium channels.
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