Receptor for glutamate. L-glutamate acts as an excitatory neurotransmitter at many synapses in the central nervous system. The postsynaptic actions of Glu are mediated by a variety of receptors that are named according to their selective agonists. Dimer. Interacts (via extracellular N-terminal domain) with CBLN1 (via C1q domain), and more weakly with CBLN2. Highest in the pyramidal and dentate granule cell layers of the hippocampus. Low in adult brain, much higher in younger animals. Belongs to the glutamate-gated ion channel (TC 1.A.10.1) family. GRID1 subfamily.