G-protein linked glutamate receptors

At least seven different G-protein linked ('metabotropic') glutamate receptors have been identified in the nervous system. Expression of these receptors in vitro suggests that they can influence a variety of second messenger systems, including adenylate cyclase and phospholipase C. The receptors fall into three separate subgroups based on sequence homologies, pharmacological specificity and functional effects. The receptors show a variable distribution in the brain and are found in both neurons and glial cells. Activation of the receptors produces a variety of effects including the regulation of K and Ca conductances as well as long-term changes in the efficacy of excitatory synaptic transmission. G-protein linked glutamate receptors probably represent an extremely widely distributed system for the regulation of synaptic function.