Delta atracotoxin
InterPro Family
Delta atracotoxin (δ-ACTX-Ar1, robustoxin, or robustotoxin) is a low-molecular mass neurotoxic polypeptide found in the venom of the Sydney funnel-web spider (Atrax robustus).
Delta atracotoxin produces potentially fatal neurotoxic symptoms in primates, by slowing the inactivation of sodium ion channels in autonomic and motor neurons. In the spiders' intended insect prey, the toxin exerts this same activity upon calcium ion channels.
The structure of atracotoxin comprises a core beta region with a cystine knot motif, a feature seen in other neurotoxic polypeptides.
History
Since 1927, records are kept of envenomations of humans by the Sydney funnel-web spider, and 14 deaths have been reported in medical literature between 1927 and 1981, when the antivenom became available. In all cases in which the sex of the spider was determined, death occurred after a bite from a male spider.
Structure
Delta atracotoxin is a 42-residue peptide toxin with the chemical formula C206H313N59O59S9. The amino acid sequence of delta atracotoxin is unusual in that it contains three consecutive cysteine residues at positions 14–16. The amino acid sequence of delta atracotoxin is:
CAKKRNWCGK NEDCCCPMKC IYAWYNQQGS CQTTITGLFK KC
Cysteine bridges exist between Cys1 and Cys15, Cys8 and Cys20, Cys14 and Cys31, and Cys16 and Cys42.
The structure consists of a small triple-stranded beta-sheet stabilized by a disulfide knot, followed by a C-terminal extension comprising three classic or inverse y-turns.
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This entry incorporates text from “Delta atracotoxin” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.