Opioid receptor random mutagenesis reveals a mechanism for G protein-coupled receptor activation.
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.
Décaillot
Fabien M
FM
Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France.
Befort
Katia
K
Filliol
Dominique
D
Yue
ShiYi
S
Walker
Philippe
P
Kieffer
Brigitte L
BL
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
D043562:Receptors, G-Protein-Coupled; D017465:Receptors, Opioid, delta; D011994:Recombinant Proteins