ChEBI: Omega-conotoxin GVIA is a heterodetic cyclic polypeptide consisting of the linear sequence Cys-Lys-Ser-Hyp-Gly-Ser-Ser-Cys-Ser-Hyp-Thr-Ser-Tyr-Asn-Cys-Cys-Arg-Ser-Cys-Asn-Hyp-Tyr-Thr-Lys-Arg-Cys-Tyr-NH2 with three disulfide bridges between cysteine residues 1-16, 8-19 and 15-26. Isolated from the venom of the fish-hunting snail Conus geographus. It has a role as a venom, a neurotoxin, a calcium channel blocker and a marine metabolite. It is a polypeptide, a heterodetic cyclic peptide, an organic disulfide and a peptidyl amide.