Molecular biology of excitatory amino acid receptors: subtypes and subunits

Glutamate receptors coupled to ion channels have been named according to their selective agonist: N-methyl-D-Aspartate (NMDA), kainate, quisqualate and alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionate (AMPA). The pharmacology of the NMDA receptor is clearly different from that of the kainate, quisqualate and AMPA receptors, thus differentiating two types: NMDA and non-NMDA receptors. Molecular cloning and expression of non-NMDA receptor subunits have now established that the different neuronal responses to kainate, quisqualate and AMPA are mediated by at least two subtypes of ligand-gated channels: one responding to the three ligands, the other responding to kainate and quisqualate but not to AMPA.