The metabotropic glutamate receptors: Structure and functions

Glutamate is the main excitatory neurotransmitter in the brain. For many years it has been considered to act only on ligand-gated receptor channels-termed NMDA, AMPA and kainate receptors-involved in the fast excitatory synaptic transmission. Recently, glutamate has been shown to regulate ion channels and enzymes producing second messengers via specific receptors coupled to G-proteins. The existence of these receptors, called metabotropic glutamate receptors, is changing our views on the functioning of fast excitatory synapses.