Metabotropic glutamate receptor 2 and metabotropic glutamate receptor 3 (mGluR2 and mGluR3)

Metabotropic glutamate receptor 2 (mGluR2) and metabotropic glutamate receptor 3 (mGluR3) are closely related members of the group II family of G protein-coupled receptors (GPCRs) primarily expressed in the central nervous system[1][4][6]. Both receptors are encoded by separate genes (*GRM2* and *GRM3*) but share considerable sequence and functional similarity. Structurally, they are seven-transmembrane domain proteins that function as constitutive dimers, with dimers required for classical glutamate-mediated activation[9]. Functionally, mGluR2 is mostly presynaptic and acts as an autoreceptor to inhibit glutamate release, while mGluR3 is found both pre- and postsynaptically and is also expressed in astrocytes[4]. Both receptors couple to Gi/o proteins, inhibiting adenylyl cyclase, decreasing cAMP levels, and modulating ion channel activity, ultimately dampening excitatory neurotransmission and playing a neuroprotective role[1][6]. Group II mGluRs have emerged as promising therapeutic targets for neuropsychiatric, neurodegenerative, and pain disorders due to their roles in regulating synaptic plasticity, neurotoxicity, and glial-neuronal interactions[5][6]. Multiple small molecules—including orthosteric agonists, antagonists, and allosteric modulators—are under investigation or have been trialed clinically for disorders such as schizophrenia and anxiety[8]. Structurally, advances in cryo-electron microscopy have revealed unique conformational changes during activation and modulation, improving the design of subtype-specific drugs[3][8].

Other names

mGlu2 (for metabotropic glutamate receptor 2)mGlu3 (for metabotropic glutamate receptor 3)Glutamate receptor, metabotropic 2 (GRM2 gene)Glutamate receptor, metabotropic 3 (GRM3 gene)Group II metabotropic glutamate receptorsGroup II mGluRs

Orthosteric agonism (binding to the glutamate site to activate the receptor); Positive allosteric modulation (PAM; enhancing receptor response to glutamate); Negative allosteric modulation (NAM; reducing receptor response); Inhibition of adenylyl cyclase via Gi/o protein coupling[6]; Regulation of voltage-gated ion channels