Glutamate-gated ion channel

The amino acid L-glutamate is the main excitatory neurotransmitter of the central nervous system (Fonnum, 1984). Glutamate exerts its excitatory effects either by activation of several G-protein-coupled metabotropic glutamate receptors or by induction of ion fluxes by different classes of ionotropic receptors. The NMDA receptor is one of those glutamate-gated ion channels which got its name from its selective artificial agonist NMDA (N-methyl-D-aspartate) and which controls slow but persistent ion fluxes of Na+, K+, and Ca2+ across the cell membrane. 

Kainate receptors represent a third class of glutamate-gated ion channel, and are made up of subunits (GluR5-7, KAl and KA2) that are homologous to AMPA receptor subunits. The cytoplasmic domains of GluR6 and KA2 have been shown to bind to the PDZl domain and to the SH3 and GK domains of PSD-95, respectively (Garcia et al., 1998). Coexpression with PSD-95 can alter the desensitization properties of kainate receptors in heterologous expression systems. 

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