L-Glutamate is the major excitatory neurotransmitter in the central nervous system. It operates through several receptors that are categorized as ionotropic (ligand-gated cation channels) or metabotropic (G-protein coupled receptors). The metabotropic glutamate receptor family includes eight members (mGluR1-8) that have been divided into three groups based on their sequence homology, pharmacology and signal transduction.

Group I of the metabotropic glutamate receptors includes the mGluR1 and mGluR5 receptors. The receptors present the typical G-protein coupled receptor (GPCR) signature topology: seven transmembrane domains with a large extracellular N-terminus and an intracellular C-terminus. The N-terminus domain of Group I receptors contains the glutamate binding site while the cytoplasmic C-terminus domain has an important role in the regulation of receptor activity through interactions with other proteins such as the Homer adaptor proteins.

mGluR1 and mGluR5 receptors signal through G_q/G₁₁, that activates phospholipase C and ultimately produces an increase in inositol trisphosphate and cytosolic Ca²⁺. Additional downstream signaling pathways include the activation of PKC and modulation of Ca²⁺ and K⁺ ion channels. Activation of signaling pathways independent of G-proteins have also been reported.

mGluR1 is predominantly expressed in nervous tissue although expression in several non-neural cell types has also been described. In the brain it is highly expressed in the hippocampus, cerebellum, olfactory bulb and thalamus.

The mGluR1 receptor is involved in several physiological processes such as neuronal development, induction of long-term potentiation (LTP) and depression (LTD) as well as in pathological disorders such as brain trauma, chronic pain, Parkinson’s and Huntington’s disease.