title: Opioid receptor random mutagenesis reveals a mechanism for G protein-coupled receptor activation.
abstract: The high resolution structure of rhodopsin has greatly enhanced current understanding of G protein-coupled receptor (GPCR) structure in the off-state, but the activation process remains to be clarified. We investigated molecular mechanisms of delta-opioid receptor activation without a preconceived structural hypothesis. Using random mutagenesis of the entire receptor, we identified 30 activating point mutations. Three-dimensional modeling revealed an activation path originating from the third extracellular loop and propagating through tightly packed helices III, VI and VII down to a VI-VII cytoplasmic switch. N- and C-terminal determinants also influence receptor activity. Findings for this therapeutically important receptor may apply to other GPCRs that respond to diffusible ligands.
authors.affiliation: Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France.
authors.forename: Fabien M
authors.initials: FM
authors.lastname: Décaillot
authors.forename: Katia
authors.initials: K
authors.lastname: Befort
authors.forename: Dominique
authors.initials: D
authors.lastname: Filliol
authors.forename: ShiYi
authors.initials: S
authors.lastname: Yue
authors.forename: Philippe
authors.initials: P
authors.lastname: Walker
authors.forename: Brigitte L
authors.initials: BL
authors.lastname: Kieffer
mesh_terms: D001665:Binding Sites; D002460:Cell Line; D006801:Humans; D066298:In Vitro Techniques; D008958:Models, Molecular; D016296:Mutagenesis; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D017465:Receptors, Opioid, delta / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D043562:Receptors, G-Protein-Coupled; D017465:Receptors, Opioid, delta; D011994:Recombinant Proteins