Metabotropic glutamate receptor group II (mGluR2/3)

Metabotropic glutamate receptor group II refers collectively to two closely related G protein-coupled receptors—metabotropic glutamate receptor 2 (mGluR2, encoded by GRM2) and metabotropic glutamate receptor 3 (mGluR3, encoded by GRM3). These receptors are primarily expressed in the central nervous system at both presynaptic terminals—where they function as autoreceptors inhibiting further release of glutamate—and postsynaptically. They play a key role in modulating synaptic transmission by coupling through Gi/o proteins that inhibit adenylyl cyclase activity. This leads to reduced cyclic AMP production, decreased calcium influx via voltage-gated channels, increased potassium conductance, and ultimately suppression of neurotransmitter release. Group II metabotropic glutamate receptors are implicated in several physiological processes including regulation of neuronal excitability, synaptic plasticity, nociceptive signaling/pain modulation, as well as broader roles such as controlling dopamine or serotonin release at heteroreceptors. Dysregulation has been linked with neuropsychiatric disorders like schizophrenia, chronic pain states, and certain cancers such as glioma. Pharmacologically targeting these receptors—with agonists like LY354740 or positive allosteric modulators like BINA—is being explored for antipsychotic therapy with a novel mechanism distinct from traditional dopamine antagonism. Selective antagonists also exist but have more limited therapeutic application. Structurally these are class C GPCRs characterized by large extracellular N-terminal domains responsible for ligand binding; they function predominantly as dimers on cell membranes. In summary, Metabotropic glutamate receptor group II is a validated therapeutic target involved in CNS signal transduction with emerging roles across neurology and oncology research fields.

Other names

Group II metabotropic glutamate receptormGluR2/3GRM2/GRM3 (gene names)Group II mGluRs

Agonists activate the Gi/o-coupled receptors to inhibit adenylyl cyclase activity, reduce cAMP levels, inhibit voltage-dependent calcium channels, activate potassium channels, and suppress presynaptic neurotransmitter release—especially glutamate. This results in decreased excitatory neurotransmission. Antagonists block these effects. Positive allosteric modulators enhance the response to endogenous glutamate without directly activating the receptor.