Short name: Nociceptin
Overlapping homologous superfamilies
- Opioid neuropeptide precursor (IPR006024)
- Nociceptin (IPR002367)
Vertebrate endogenous opioid neuropeptides are released by post-translational proteolytic cleavage of precursor proteins. The precursors consist of the following components: a signal sequence that precedes a conserved region of about 50 residues; a variable-length region; and the sequence of the neuropeptide itself. Three types of precursor are known: preproenkephalin A (gene PENK), which is processed to produce 6 copies of Met-enkephalin, plus Leu-enkephalin; preproenkephalin B (gene PDYN), which is processed to produce neoendorphin, dynorphin, leumorphin, rimorphin and Leu-enkephalin; and prepronocipeptin (gene PNOC), whose processing produces nociceptin (orphanin FQ) and two other potential neuropeptides.
Sequence analysis reveals that the conserved N-terminal region of the precursors contains 6 cysteines, which are probably involved in disulphide bond formation. It is speculated that this region might be important for neuropeptide processing [PMID: 8710928].
Nociceptin (or orphanin FQ) is a natural agonist of opioid receptor-like receptor [PMID: 8710928]. The peptide is derived from the prepronociceptin precursor, whose gene is predominantly transcribed in the central nervous system (brain and spinal cord) and, weakly, in the ovary (the sole peripheral organ that expresses the gene) [PMID: 8710928]. Studies on Rattus norvegicus (Rat) and Mus musculus (Mouse) nociceptin suggest that the protein functions not only as a neuropeptide precursor but also as an important component in neuronal differentiation [PMID: 7503733].
- PR01031 (ORPHNNPRCRSR)