Nociceptin is the ligand of the opioid receptor-like receptor (OPRL1). It may act as a transmitter in the brain by modulating nociceptive and locomotor behavior. Nociceptin is also involved in neuronal differentiation and development. Nociceptin is a potent anti-analgesic. Nociceptin is a 17-aa peptide processed from the prepronociceptin precursor that is cleaved in 3 chains, nocistatin, nociceptin and orphanin FQ2.Human: H-Phe-Gly-Gly-Phe-Thr-Gly-Ala-Arg-Lys-Ser-Ala-Arg-Lys-Leu-Ala-Asn-Gln-OH or H-FGGFTGARKSARKLANQ-OH