Expressed by the venom duct. Is mostly present the middle of the duct (part 3, 85%) and just after (part 4, 11%). The cysteine framework is III (CC-C-C-CC). Classified in the M-1 branch, since 1 residue stands between the fourth and the fifth cysteine residues. Contains 3 disulfide bonds. Belongs to the conotoxin M superfamily.