Protein KINASE C–Dependent Remodeling of Glutamate Transporter Function

Schematic representation of a glutamatergic synapse. Synaptic release of glutamate results in activation of several different types of glutamate receptors that are situated on the post-synaptic neuron, on the presynaptic terminal, and the surrounding glial cells. For simplicity, receptors are only shown on the post-synaptic terminal. Glutamate is cleared from the synaptic space by transporters that are enriched on the postsynaptic termini and on the glial processes that sheath the synapse. Neurons primarily express the “neuronal” transporters EAAC1 and EAAT4, and astrocytes mainly express the “glial” transporters GLAST and GLT-1. The concentration of glutamate in the synaptic cleft has been estimated to be as high as 10 mM during periods of synaptic activation, but under resting conditions transporters probably reduce concentrations to less than 1 μ M.