This peptide is amino acids 1 to 7 fragment of nociceptin (orphanin FQ, OFQ/N). The complete OFQ/N sequence contains pairs of basic amino acids that might imply additional processing of the peptide to this OFQ/N 1 to 7 fragment. This truncated peptide is functionally active when administered in vivo producing analgesia that is reversed by opioid antagonists. The peptide shows no appreciable affinity for any of the traditional opioid receptors.
Mogil, J. and Pasternak, G. Pharmacol. Rev. 53, 381 (2001).