The AMPA receptor is a non-NMDA-type ionotropic transmembrane receptor for glutamate that mediates fast synaptic transmission in the CNS. AMPARs are composed of four types of subunits, designated as GluR1, GluR2, GluR3 and GluR4, which combine to form tetramers (3, 4).
GluR2 is possibly the most important AMPA receptor subunit, responsible for AMPA receptor rectifying properties, control of ion flow and in particular, the influx of calcium. The majority of GluR2 in the CNS is expressed in the GluR2 form, containing a critical arginine residue in the transmembrane region 2 domain, thereby rendering native AMPA receptors impermeable to calcium (5).