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Purification and functional reconstitution of monomeric mu-opioid receptors: allosteric modulation of agonist binding by Gi2.

ABSTRACT: Despite extensive characterization of the mu-opioid receptor (MOR), the biochemical properties of the isolated receptor remain unclear. In light of recent reports, we proposed that the monomeric form of MOR can activate G proteins and be subject to allosteric regulation. A mu-opioid receptor fused to yellow fluorescent protein (YMOR) was constructed and expressed in insect cells. YMOR binds ligands with high affinity, displays agonist-stimulated [(35)S]guanosine 5'-(gamma-thio)triphosphate binding to Galpha(i), and is allosterically regulated by coupled G(i) protein heterotrimer both in insect cell membranes and as purified protein reconstituted into a phospholipid bilayer in the form of high density lipoprotein particles. Single-particle imaging of fluorescently labeled receptor indicates that the reconstituted YMOR is monomeric. Moreover, single-molecule imaging of a Cy3-labeled agonist, [Lys(7), Cys(8)]dermorphin, illustrates a novel method for studying G protein-coupled receptor-ligand binding and suggests that one molecule of agonist binds per monomeric YMOR. Together these data support the notion that oligomerization of the mu-opioid receptor is not required for agonist and antagonist binding and that the monomeric receptor is the minimal functional unit in regard to G protein activation and strong allosteric regulation of agonist binding by G proteins.

SUBMITTER: Kuszak AJ

PROVIDER: S-EPMC2785361 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

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Purification and functional reconstitution of monomeric mu-opioid receptors: allosteric modulation of agonist binding by Gi2.

Kuszak Adam J AJ Pitchiaya Sethuramasundaram S Anand Jessica P JP Mosberg Henry I HI Walter Nils G NG Sunahara Roger K RK

The Journal of biological chemistry 20090619 39

Despite extensive characterization of the mu-opioid receptor (MOR), the biochemical properties of the isolated receptor remain unclear. In light of recent reports, we proposed that the monomeric form of MOR can activate G proteins and be subject to allosteric regulation. A mu-opioid receptor fused to yellow fluorescent protein (YMOR) was constructed and expressed in insect cells. YMOR binds ligands with high affinity, displays agonist-stimulated [(35)S]guanosine 5'-(gamma-thio)triphosphate bindi ...[more]

PMID: 19542234

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Dataset Information

Purification and functional reconstitution of monomeric mu-opioid receptors: allosteric modulation of agonist binding by Gi2.

Publications

Purification and functional reconstitution of monomeric mu-opioid receptors: allosteric modulation of agonist binding by Gi2.

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