Expressed by the venom 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. Reg12e and reg3e are conotoxins with identical sequences, but different post-translational modifications. Reg12e is C-terminally amidated, while reg3e is not. Belongs to the conotoxin M superfamily.