Nociceptin/Orphanin FQ Antibodies

A search for related receptors by homology cloning led to the identification of a fourth member of the opioid receptor family. Since none of the then known endogenous opioid peptides interacted with this receptor, a search for an endogenous ligand for this orphan receptor was initiated. Two groups independently isolated and characterized the same novel endogenous peptide from brain extracts. This peptide was named by the two groups nociceptin or orphanin FQ (hereafter abbreviated as N/OFQ). N/OFQ is the product of a precursor protein encoded by a novel gene with significant sequence homology to the genes encoding prodynorphin, proenkephalin and pro-opiomelanocortin. These results suggest that a system utilising the peptide N/OFQ has developed, possibly as a result of gene duplication followed by subsequent evolutionary modification. The novel system is structurally related to the endogenous opioid systems, yet is pharmacologically distinct in that there is no significant cross-activation by opioid peptides.