Glutamate is a central molecule in metabolism. It is the product in the transamination reaction of alpha-ketoglutarate. It can also be formed out of glutamine and water. Glutamate itself is a precursor of gamma aminobutyric acid (GABA) in the brain.
Four different types of glutamate receptors have been identified so far. There are 3 ion channels or ionotropic receptors: NDMA receptor, kainate receptor and AMPA receptor. The mGluR is a metabotropic receptor which is G-protein coupled. All 4 receptor types can be subdivided into subtypes.