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 > domoate > L-glutamate >> AMPA >> NMDA = 1S,3R-ACPD. Tetramer of two or more different subunits. Associates with GRIK1 (both edited and unedited versions), GRIK2, or GRIK3 to form functional channels. Homomeric associations do not produce any channel activity (By similarity). Belongs to the glutamate-gated ion channel (TC 1.A.10.1) family. GRIK5 subfamily.