omega-Atracotoxin (ω-atracotoxin) is an insect-specific neurotoxin produced by the Blue Mountains funnel-web spider. Its phylogenetic specificity derives from its ability to antagonise insect, but not vertebrate, voltage-gated calcium channels. Two spatially proximal amino acid residues, Asn(27) and Arg(35), form a contiguous molecular surface that is essential for toxin activity. It has been proposed that this surface of the beta-hairpin is a key site for interaction of the toxin with insect calcium channels.
^King GF, Fletcher JI, Tedford HW (2001). "Functional significance of the beta hairpin in the insecticidal neurotoxin omega-atracotoxin-Hv1a". J. Biol. Chem. 276 (28): 26568–26576. doi:10.1074/jbc.M102199200. PMID11313356.