Glutamate receptors mediate most excitatory neurotransmission in the brain and play an important role in neural plasticity, neural development and neurodegeneration. Ionotropic glutamate receptors are categorized into NMDA receptors and kainate/AMPA receptors, both of which contain glutamate-gated, cation-specific ion channels. Kainate/AMPA receptors are co-localized with NMDA receptors in many synapses and consist of the structurally related subunits GluR-1 to -7, KA1 and KA2. KA1 (also designated EEA1) and KA2 (also designated EEA2) form heteromeric receptors with GluR subunits when coexpressed, forming ion channels with various properties. The kainate/AMPA receptors are primarily responsible for the fast excitatory neuro-transmission by glutamate.