Patent ID: 8273358

Claim:
A recombinant single-chain polypeptide comprising: a) a first amino acid sequence region comprising i) a first domain comprising a binding element comprising an opioid peptide able to preferentially interact with an opioid peptide receptor under physiological conditions; and ii) a second domain comprising a translocation element comprising a Clostridial neurotoxin translocation domain able to facilitate the transfer of a Clostridial toxin light chain across a vesicular membrane; b) a second amino acid sequence region comprising a therapeutic element comprising a Clostridial neurotoxin light chain having biological activity when released into the cytoplasm of said target cell; and c) a third amino acid sequence region comprising an exogenous protease cleavage site; wherein said first and second amino acid sequence regions are separated by said third amino acid sequence region, wherein said exogenous protease cleavage site comprises a tobacco vein mottling virus protease cleavage site selected from the group consisting of: SEQ ID NO: 132, SEQ ID NO: 133, SEQ ID NO: 134, SEQ ID NO: 135, SEQ ID NO: 136, and SEQ ID NO: 137.