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. This receptor binds kainate > quisqualate > glutamate >> AMPA. Forms a heteromeric channel with GRIK1 or GRIK3. Strong expression in hippocampal CA3 pyramidal cells. Low expression in hippocampal dentate granule cells, in layers II, V and VI of the cortex, and in cerebellar Purkinje cells. No expression in the striatum, reticular thalamus, hypothalamus or amygdaloid complex. Expressed at embryonic day 15 in brain and spinal cord. At embryonic day 19 expression accumulates in the hippocampal formation. Prominent expression in the subicular cortex at postnatal days P1, P8 and P15 but then markedly reduced in the adult. Belongs to the glutamate-gated ion channel (TC 1.A.10.1) family. GRIK4 subfamily.