Back to Search
Start Over
Glutamate acts as a partial inverse agonist to metabotropic glutamate receptor with a single amino acid mutation in the transmembrane domain.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2013 Apr 05; Vol. 288 (14), pp. 9593-9601. Date of Electronic Publication: 2013 Feb 18. - Publication Year :
- 2013
-
Abstract
- Metabotropic glutamate receptor (mGluR), a prototypical family 3 G protein-coupled receptor (GPCR), has served as a model for studying GPCR dimerization, and growing evidence has revealed that a glutamate-induced dimeric rearrangement promotes activation of the receptor. However, structural information of the seven-transmembrane domain is severely limited, in contrast to the well studied family 1 GPCRs including rhodopsins and adrenergic receptors. Homology modeling of mGluR8 transmembrane domain with rhodopsin as a template suggested the presence of a conserved water-mediated hydrogen-bonding network between helices VI and VII, which presumably constrains the receptor in an inactive conformation. We therefore conducted a mutational analysis to assess structural similarities between mGluR and family 1 GPCRs. Mutational experiments confirmed that the disruption of the hydrogen-bonding network by T789Y(6.43) mutation induced high constitutive activity. Unexpectedly, this high constitutive activity was suppressed by glutamate, the natural agonist ligand, indicating that glutamate acts as a partial inverse agonist to this mutant. Fluorescence energy transfer analysis of T789Y(6.43) suggested that the glutamate-induced reduction of the activity originated not from the dimeric rearrangement but from conformational changes within each protomer. Double mutational analysis showed that the specific interaction between Tyr-789(6.43) and Gly-831(7.45) in T789Y(6.43) mutant was important for this phenotype. Therefore, the present study is consistent with the notion that the metabotropic glutamate receptor shares a common activation mechanism with family 1 GPCRs, where rearrangement between helices VI and VII causes the active state formation.
- Subjects :
- Amino Acid Motifs
Amino Acid Sequence
Animals
Cattle
DNA Mutational Analysis
Fluorescence Resonance Energy Transfer methods
Glutamic Acid chemistry
Glycine chemistry
HEK293 Cells
Humans
Molecular Conformation
Molecular Sequence Data
Mutagenesis, Site-Directed
Mutation
Phenotype
Protein Binding
Protein Conformation
Protein Structure, Tertiary
Proteins chemistry
Rhodopsin genetics
Sequence Homology, Amino Acid
Tyrosine chemistry
Amino Acids chemistry
Glutamic Acid metabolism
Receptors, Metabotropic Glutamate agonists
Subjects
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 288
- Issue :
- 14
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 23420844
- Full Text :
- https://doi.org/10.1074/jbc.M112.437780