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-3 branch, since 3 residues stand between the fourth and the fifth cysteine residues. Contains 3 disulfide bonds. Two peptides are produced from this precursor. Conotoxin Tx3.5-b is amidated at Cys-63, conotoxin Tx3.5-a has an unmodified C-terminus. With amidation at Cys-63. Belongs to the conotoxin M superfamily.