Closed state of both binding domains of homodimeric mGlu receptors is required for full activity.
Membrane receptors, key components in signal transduction, often function as dimers. These include some G protein-coupled receptors such as metabotropic glutamate (mGlu) receptors that have large extracellular domains (ECDs) where agonists bind. How agonist binding in dimeric ECDs activates the effector domains remains largely unknown. The structure of the dimeric ECDs of mGlu(1) solved in the presence of agonist revealed two specific conformations in which either one or both protomers are in an agonist-stabilized closed form. Here we examined whether both conformations correspond to an active form of the full-length receptor. Using a system that allows the formation of dimers made of a wild-type and a mutant subunit, we show that the closure of one ECD per dimer is sufficient to activate the receptor, but the closure of both ECDs is required for full activity.
Kniazeff
Julie
J
Laboratory of Functional Genomics, Department of Molecular Pharmacology, Centre National de la Recherche Scientifique, Unite Propre de Recherche 2580, 141 rue de la Cardonille, 34094 Montpellier Cedex 5, France.
Bessis
Anne-Sophie
AS
Maurel
Damien
D
Ansanay
Hervé
H
Prézeau
Laurent
L
Pin
Jean-Philippe
JP
D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D018360:Crystallography, X-Ray; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D031541:Fluorescence Resonance Energy Transfer; D006801:Humans; D007295:Inositol Phosphates / Q000737:chemistry; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D018080:Receptors, GABA-B / Q000737:chemistry; D018094:Receptors, Metabotropic Glutamate / Q000737:chemistry*; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection
D007295:Inositol Phosphates; D018080:Receptors, GABA-B; D018094:Receptors, Metabotropic Glutamate; D002118:Calcium