A remotely related group of atracotoxins operate by opening sodium channels. Delta atracotoxin produces potentially fatal neurotoxic symptoms in primates by slowing the inactivation of voltage-gated sodium channels.[2] The structure of atracotoxin comprises a core beta region containing a triple-stranded a thumb-like extension protruding from the beta region and a C-terminal helix. The beta region contains a cystine knot motif, a feature seen in other neurotoxic polypeptides[2] and other spider toxins, of the CSTX family.
Spider potassium channel inhibitory toxins is another group of spider toxins. A representative of this group is hanatoxin, a 35 amino acid peptide toxin which was isolated from Chilean rose tarantula (Grammostola rosea, syn.G. spatulata) venom. It inhibits the drk1 voltage-gated potassium channel by altering the energetics of gating.[3] See also Huwentoxin-1 InterPro: IPR013140.
^ abMackay JP, King GF, Fletcher JI, Chapman BE, Howden ME (1997). "The structure of versutoxin (delta-atracotoxin-Hv1) provides insights into the binding of site 3 neurotoxins to the voltage-gated sodium channel". Structure. 5 (11): 1525–1535. doi:10.1016/S0969-2126(97)00301-8. PMID9384567.
^Shimada I, Sato K, Takahashi H, Kim JI, Min HJ, Swartz KJ (2000). "Solution structure of hanatoxin1, a gating modifier of voltage-dependent K(+) channels: common surface features of gating modifier toxins". J. Mol. Biol. 297 (3): 771–780. doi:10.1006/jmbi.2000.3609. PMID10731427.
Further reading
Kim JI, Konishi S, Iwai H, Kohno T, Gouda H, Shimada I, Sato K, Arata Y (July 1995). "Three-dimensional solution structure of the calcium channel antagonist omega-agatoxin IVA: consensus molecular folding of calcium channel blockers". J. Mol. Biol. 250 (5): 659–71. doi:10.1006/jmbi.1995.0406. PMID7623383.