Trafficking and Targeting of XXXX Receptors

@entity11588 @entity2227 @entity6806 @entity4176 @entity21413 @entity140 @entity143 @entity21412 @entity13069
At glutamatergic synapses, @entity143 receptors (NMDARs) are localized with other ionotropic @entity2227 receptors [ @entity140 receptors (AMPARs) and @entity4176 receptors] and with metabotropic @entity2227 receptors. Targeting the necessary number of NMDARs to the proper sites at synapses is critical for normal glutamatergic neurotransmission and synaptic plasticity. Additional diversity of NMDAR responses arises from the complexity of subunit composition and variations in localization. Thus, the mechanisms of NMDAR trafficking and targeting must address the complex needs of neurons. For example, NMDARs must be transported to different subcellular sites because some receptors are localized to synaptic sites (pre- and postsynaptic) while others are localized extrasynaptically [1   4]. NMDAR subunit expression differs as a function of brain region and developmental age [5   7]. Subunit composition may determine subcellular localization, i.e., in adults, @entity11588 -containing receptors are enriched at synapses while extrasynaptic receptors are predominantly @entity13069 -containing complexes [1,2,4]. Furthermore, evidence indicates the incorporation of more than one type of NR2 subunit in each complex (tri-heteromeric @entity6806 /NR2X/NR2Y) such as @entity6806 / @entity11588 / @entity13069 receptors in hippocampal neuron synapses, @entity6806 / @entity11588 / @entity21413 in cerebellar granule cell synapses, and @entity6806 / @entity13069 / @entity21412 in substantia nigra dopaminergic neurons [8]. Finally, different NMDARs may be expressed at different synapses within the same neuron [4]. Thus, the mechanisms of NMDAR trafficking must be varied and well regulated to meet the needs of neurons.
