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 (By. similarity). May function in the light response in the retina (PubMed:26427409). Homodimer; disulfide-linked (By similarity). The PPXXF motif binds HOMER1, HOMER2 and HOMER3. Interacts with TAMALIN (By similarity). Interacts with RYR1, RYR2, ITPR1, SHANK1 and SHANK3. Interacts with SHIA1 (By similarity). Expressed in the striatum (at protein level). Belongs to the G-protein coupled receptor 3 family.