G-protein coupled receptor for glutamate. Ligand binding causes a conformation change that triggers signaling via guanine nucleotide-binding proteins (G proteins) and modulates the activity of down-stream effectors. Signaling activates a phosphatidylinositol-calcium second messenger system. May participate in the central action of glutamate in the CNS, such as long-term potentiation in the hippocampus and long-term depression in the cerebellum (PubMed:24603153, PubMed:28886343, PubMed:7476890). May function in the light response in the retina (By similarity). Signaling is inhibited by the antagonist LY341495. The LY341495 binding site partially overlaps with the glutamate binding site. Signaling is also inhibited by synthetic allosteric regulators, such as FITM (4-fluoro-N-(4-(6-(isopropylamino)pyrimidin-4-yl)thiazol-2-yl)-N-methylbenzamide) that bind in a pocket between the transmembrane helices. Homodimer; disulfide-linked (PubMed:24603153). The PPXXF motif binds HOMER1, HOMER2 and HOMER3. Interacts with TAMALIN (By similarity). Interacts with RYR1, RYR2, ITPR1, SHANK1 and SHANK3. Interacts with SIAH1 (By similarity). Detected in brain. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the G-protein coupled receptor 3 family.