L-glutamate is the major excitatory neurotransmitter in the central nervous system and activates both ionotropic and metabotropic glutamate receptors. Glutamatergic neurotransmission is involved in most aspects of normal brain function and can be perturbed in many neuropathologic conditions. GRM2 is linked to the inhibition of the cyclic AMP cascade, included in group II metabotropic glutamate receptors.