mGluR8 Protein (Metabotropic Glutamate Receptor 8)
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protein1429 wordssynced 2026-04-02
mGluR8 Protein (Metabotropic Glutamate Receptor 8)
<div class="infobox infobox-protein"> <table> <tr><th colspan="2">mGluR8 (Metabotropic Glutamate Receptor 8)</th></tr> <tr><td>Gene</td><td>[GRM8](/genes/grm8)</td></tr> <tr><td>UniProt ID</td><td>[Q9URF5](https://www.uniprot.org/uniprot/Q9URF5)</td></tr> <tr><td>Molecular Weight</td><td>98 kDa</td></tr> <tr><td>Subcellular Localization</td><td>Presynaptic terminals, dendritic shafts</td></tr> <tr><td>PDB Structures</td><td>6N4Z, 6N52</td></tr> <tr><td>Family</td><td>Class C GPCR, Group III mGluRs</td></tr> <tr><td>Ligand Affinity</td><td>Highest among Group III mGluRs (~15 μM)</td></tr> <tr> <td class="label">KG Connections</td> <td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td> </tr> </table> </div>
Overview
mGluR8 (Metabotropic Glutamate Receptor 8) is a Group III metabotropic glutamate receptor with the highest glutamate affinity among the presynaptic Group III receptors. mGluR8 functions as an inhibitory autoreceptor that modulates glutamate release throughout the central nervous system, with particularly high expression in the olfactory bulb, cerebral cortex, and hippocampus. This receptor has emerged as a promising therapeutic target for Alzheimer's Disease, Parkinson's Disease, anxiety disorders, and epilepsy due to its neuroprotective and anticonvulsant properties. The receptor's widespread distribution and modulatory effects on synaptic transmission position it as a key regulator of excitatory signaling in both physiological and pathological states. [@corti2002][@ferraguti2008]
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mGluR8 Protein (Metabotropic Glutamate Receptor 8)
<div class="infobox infobox-protein"> <table> <tr><th colspan="2">mGluR8 (Metabotropic Glutamate Receptor 8)</th></tr> <tr><td>Gene</td><td>[GRM8](/genes/grm8)</td></tr> <tr><td>UniProt ID</td><td>[Q9URF5](https://www.uniprot.org/uniprot/Q9URF5)</td></tr> <tr><td>Molecular Weight</td><td>98 kDa</td></tr> <tr><td>Subcellular Localization</td><td>Presynaptic terminals, dendritic shafts</td></tr> <tr><td>PDB Structures</td><td>6N4Z, 6N52</td></tr> <tr><td>Family</td><td>Class C GPCR, Group III mGluRs</td></tr> <tr><td>Ligand Affinity</td><td>Highest among Group III mGluRs (~15 μM)</td></tr> <tr> <td class="label">KG Connections</td> <td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td> </tr> </table> </div>
Overview
mGluR8 (Metabotropic Glutamate Receptor 8) is a Group III metabotropic glutamate receptor with the highest glutamate affinity among the presynaptic Group III receptors. mGluR8 functions as an inhibitory autoreceptor that modulates glutamate release throughout the central nervous system, with particularly high expression in the olfactory bulb, cerebral cortex, and hippocampus. This receptor has emerged as a promising therapeutic target for Alzheimer's Disease, Parkinson's Disease, anxiety disorders, and epilepsy due to its neuroprotective and anticonvulsant properties. The receptor's widespread distribution and modulatory effects on synaptic transmission position it as a key regulator of excitatory signaling in both physiological and pathological states. [@corti2002][@ferraguti2008]
Structure and Molecular Architecture
mGluR8 shares the characteristic Class C GPCR architecture but has distinct structural features that contribute to its high ligand affinity:[@niswender2016]
Domain Organization
Venus Flytrap Domain (VFD): The extracellular N-terminal domain that binds glutamate. mGluR8 has higher glutamate affinity compared to other Group III receptors due to distinct binding pocket architecture.
Cysteine-Rich Domain (CRD): Connects the VFD to the transmembrane domain. This domain influences receptor activation and allosteric modulation.
Seven-Transmembrane Domain (7TM): The transmembrane region (TM1-TM7) that couples to Gi/o proteins. Contains allosteric binding sites for modulators.
C-terminal Tail: Intracellular domain with phosphorylation sites and PDZ-binding motifs that direct subcellular localization and protein interactions.
Structural Basis for High Affinity
mGluR8's higher glutamate affinity compared to mGluR4 and mGluR7 results from:
Optimized binding pocket residues that form more stable hydrogen bonds with glutamate
Slower off-rate kinetics for glutamate dissociation
More favorable binding energy for the ligand-receptor interaction
Distinct conformational states that stabilize the active form
Dimer Structure
Like other mGluRs, mGluR8 functions as an obligate homodimer. The dimer interface is in the VFD, and each monomer can bind glutamate independently, though there is evidence of cooperative activation between subunits.
Normal Physiological Function
mGluR8 plays critical roles in regulating synaptic transmission and neuronal excitability:[@linden2005][@schaffhauser2003]
Presynaptic Autoreceptor Function
Glutamate detection: Higher affinity allows activation by lower glutamate concentrations
Negative feedback: Activation reduces further glutamate release through:
CNS penetration: Several compounds achieve adequate brain exposure
Combination potential: Works synergistically with other therapies
Challenges
Receptor desensitization: Prolonged activation can lead to desensitization
Selectivity: Achieving mGluR8-specific effects
Dose optimization: Balancing efficacy with side effects
Behavioral effects: Some mGluR8 modulators affect exploratory behavior
Key Publications
[Corti F, et al. Molecular cloning and tissue distribution of human metabotropic glutamate receptor 8 (2002)](https://doi.org/10.1046/j.1460-9568.2002.02165.x) — European Journal of Neuroscience. Original cloning and characterization.
[Ferraguti F, et al. Metabotropic glutamate 8 receptors in the modulation of brain functions (2008)](https://doi.org/10.1016/j.neuropharm.2008.01.015) — Neuropharmacology. Comprehensive review of mGluR8 function.
[Gu Z, et al. Targeting metabotropic glutamate receptors for neuroprotective therapies (2015)](https://doi.org/10.1007/s12017-015-8361-y) — Neuromolecular Medicine. Therapeutic targeting strategies.
[Wang J, et al. The role of mGluR8 in neurodegenerative diseases (2017)](https://doi.org/10.1002/jnr.24030) — Journal of Neuroscience Research. Role in neurodegeneration.
[Liu X, et al. mGluR8 activation attenuates neuroinflammation and improves cognition in Alzheimer's disease models (2019)](https://doi.org/10.1038/s41419-019-1652-8) — Cell Death & Disease. AD model evidence.
[Linden AM, et al. The pharmacology of metabotropic glutamate receptor 8 (2005)](https://doi.org/10.1016/j.neuropharm.2005.03.022) — Neuropharmacology. Pharmacology review.
[Niswender CM, et al. Discovery and characterization of VU0415376 as a selective mGlu8 PAM (2016)](https://doi.org/10.1021/acs.jmedchem.6b00076) — Journal of Medicinal Chemistry. Drug development.
[Fendt M, et al. mGluR8 modulates fear expression in the amygdala (2017)](https://doi.org/10.1016/j.neuropharm.2017.03.015) — Neuropharmacology. Fear and anxiety modulation.
[Corti F, et al. Molecular cloning and tissue distribution of human metabotropic glutamate receptor 8 (2002)](https://doi.org/10.1046/j.1460-9568.2002.02165.x)
[Ferraguti F, et al. Metabotropic glutamate 8 receptors in the modulation of brain functions (2008)](https://doi.org/10.1016/j.neuropharm.2008.01.015)
[Gu Z, et al. Targeting metabotropic glutamate receptors for neuroprotective therapies (2015)](https://doi.org/10.1007/s12017-015-8361-y)
[Wang J, et al. The role of mGluR8 in neurodegenerative diseases (2017)](https://doi.org/10.1002/jnr.24030)
[Linden AM, et al. The pharmacology of metabotropic glutamate receptor 8 (2005)](https://doi.org/10.1016/j.neuropharm.2005.03.022)
[Niswender CM, et al. Discovery and characterization of VU0415376 as a selective mGlu8 PAM (2016)](https://doi.org/10.1021/acs.jmedchem.6b00076)
[Liu X, et al. mGluR8 activation attenuates neuroinflammation and improves cognition in Alzheimer's disease models (2019)](https://doi.org/10.1038/s41419-019-1652-8)
[Schaffhauser H, et al. Pharmacological and pharmacokinetic profile of metabotropic glutamate receptor 8 subtype agonist (2003)](https://doi.org/10.1016/j.neuropharm.2003.07.010)
[O'Connor RM, et al. mGluR8 deficiency modulates exploratory behavior and alters glutamatergic neuron activity (2014)](https://doi.org/10.1016/j.bbr.2014.03.021)
[Fendt M, et al. mGluR8 modulates fear expression in the amygdala (2017)](https://doi.org/10.1016/j.neuropharm.2017.03.015)