Omega-conotoxins act at presynaptic membranes, they bind and block voltage-gated calcium channels (Cav). In vivo, this toxin is a potent paralytic toxic in lower vertebrate species, but it is much less effective in mammals. Expressed by the venom duct. The presence of a 'disulfide through disulfide knot' structurally defines this protein as a knottin. The cysteine framework is VI/VII (C-C-CC-C-C). On fish, this toxin causes paralysis and death on intramuscular injection at doses of approximately 20 pmol/g. It does not kill mice even at extremely high doses. Belongs to the conotoxin O1 superfamily. Thr-72 is not followed in the nucleotide sequence by the expected Gly residue required to produce amidation.