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Biochem Biophys Res Commun. 1997 Jan 13;230(2):462-5.

Biochemical evidence for orphanin FQ/nociceptin receptor heterogeneity in mouse brain.

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  • 1The George C. Cotzias Laboratory of Neuro-Oncology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.

Abstract

A recently identified novel peptide, orphanin FQ/nociceptin (OFQ/N), is an endogenous ligand for a unique member of the cloned opioid receptor family. Saturation studies in mouse brain membranes reveal curvilinear Scatchard plots with both a higher (KD 3.8 pM, Bmax 31.6 fmol/mg protein) and a lower (KD 896 pM, Bmax 233 fmol/mg protein) affinity site in brain tissue, compared to only a single site in transfected CHO cells (KD 36 pM). Competition studies confirm the high affinity of OFQ/N for this site, but shallow Hill slopes suggest heterogeneity. Traditional opioids have poor affinity for this receptor and OFQ/N and its fragments do not label traditional opioid receptors. In brain homogenates, both OFQ/N and OFQ/N(1-11) inhibit forskolin-stimulated camp accumulation with IC50 values of 1 nM or less, an action which is readily reversed by opioid antagonists. OFQ/N(1-7) shows little activity. Together, these studies suggest the presence of heterogeneous, functionally active OFQ/N receptors in mouse brain.

PMID:
9016803
[PubMed - indexed for MEDLINE]
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