Expressed by the venom duct. Is present in all duct parts with a highest content in part 2 (proximal of the venom bulb) and then decreases in concentration toward the end of the duct. 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. The truncated conotoxin tx3h exists in two forms, one is amidated, whereas the other is non-amidated. The conotoxin tx3h also exists in two forms, one is amidated and the other is brominated but not amidated. Belongs to the conotoxin M superfamily.