Delta-Atracotoxin (dACTX)

Delta atracotoxin is a low-molecular-weight 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 potassium and calcium ion channels. The structure of atracotoxin comprises a core beta region with a cystine knot motif, a feature seen in other neurotoxic polypeptides. Robustoxin (RBX) is a 42-residue peptide toxin. The amino acid sequence of RBX is unusual in that it contains three consecutive cysteine residues at positions 14–16. The Amino acid sequence of RBX is: cakkrnwcgk nedcccpmkc iyawynqqgs cqttitglfk kc A cysteine bridge exists between Cys1 and Cys15, Cys8 and Cys20, Cys14 and Cys31 and between Cys16 and Cys42.