| Structural highlights
Function
OPRK_HUMAN G-protein coupled opioid receptor that functions as receptor for endogenous alpha-neoendorphins and dynorphins, but has low affinity for beta-endorphins. Also functions as receptor for various synthetic opioids and for the psychoactive diterpene salvinorin A. Ligand binding causes a conformation change that triggers signaling via guanine nucleotide-binding proteins (G proteins) and modulates the activity of down-stream effectors, such as adenylate cyclase. Signaling leads to the inhibition of adenylate cyclase activity. Inhibits neurotransmitter release by reducing calcium ion currents and increasing potassium ion conductance. Plays a role in the perception of pain. Plays a role in mediating reduced physical activity upon treatment with synthetic opioids. Plays a role in the regulation of salivation in response to synthetic opioids. May play a role in arousal and regulation of autonomic and neuroendocrine functions.[1] [2] [3] [4]
Publication Abstract from PubMed
The kappa-opioid receptor (KOR) has emerged as an attractive drug target for pain management without addiction, and biased signaling through particular pathways of KOR may be key to maintaining this benefit while minimizing side-effect liabilities. As for most G protein-coupled receptors (GPCRs), however, the molecular mechanisms of ligand-specific signaling at KOR have remained unclear. To better understand the molecular determinants of KOR signaling bias, we apply structure determination, atomic-level molecular dynamics (MD) simulations, and functional assays. We determine a crystal structure of KOR bound to the G protein-biased agonist nalfurafine, the first approved KOR-targeting drug. We also identify an arrestin-biased KOR agonist, WMS-X600. Using MD simulations of KOR bound to nalfurafine, WMS-X600, and a balanced agonist U50,488, we identify three active-state receptor conformations, including one that appears to favor arrestin signaling over G protein signaling and another that appears to favor G protein signaling over arrestin signaling. These results, combined with mutagenesis validation, provide a molecular explanation of how agonists achieve biased signaling at KOR.
Molecular mechanism of biased signaling at the kappa opioid receptor.,El Daibani A, Paggi JM, Kim K, Laloudakis YD, Popov P, Bernhard SM, Krumm BE, Olsen RHJ, Diberto J, Carroll FI, Katritch V, Wunsch B, Dror RO, Che T Nat Commun. 2023 Mar 11;14(1):1338. doi: 10.1038/s41467-023-37041-7. PMID:36906681[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Li JG, Chen C, Liu-Chen LY. Ezrin-radixin-moesin-binding phosphoprotein-50/Na+/H+ exchanger regulatory factor (EBP50/NHERF) blocks U50,488H-induced down-regulation of the human kappa opioid receptor by enhancing its recycling rate. J Biol Chem. 2002 Jul 26;277(30):27545-52. Epub 2002 May 9. PMID:12004055 doi:http://dx.doi.org/10.1074/jbc.M200058200
- ↑ Wu H, Wacker D, Mileni M, Katritch V, Han GW, Vardy E, Liu W, Thompson AA, Huang XP, Carroll FI, Mascarella SW, Westkaemper RB, Mosier PD, Roth BL, Cherezov V, Stevens RC. Structure of the human kappa-opioid receptor in complex with JDTic. Nature. 2012 Mar 21;485(7398):327-32. doi: 10.1038/nature10939. PMID:22437504 doi:10.1038/nature10939
- ↑ Simonin F, Gaveriaux-Ruff C, Befort K, Matthes H, Lannes B, Micheletti G, Mattei MG, Charron G, Bloch B, Kieffer B. kappa-Opioid receptor in humans: cDNA and genomic cloning, chromosomal assignment, functional expression, pharmacology, and expression pattern in the central nervous system. Proc Natl Acad Sci U S A. 1995 Jul 18;92(15):7006-10. PMID:7624359
- ↑ Mansson E, Bare L, Yang D. Isolation of a human kappa opioid receptor cDNA from placenta. Biochem Biophys Res Commun. 1994 Aug 15;202(3):1431-7. PMID:8060324
- ↑ El Daibani A, Paggi JM, Kim K, Laloudakis YD, Popov P, Bernhard SM, Krumm BE, Olsen RHJ, Diberto J, Carroll FI, Katritch V, Wünsch B, Dror RO, Che T. Molecular mechanism of biased signaling at the kappa opioid receptor. Nat Commun. 2023 Mar 11;14(1):1338. PMID:36906681 doi:10.1038/s41467-023-37041-7
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