Distribution of Extrasynaptic NMDA Receptors on Neurons

Figure 4

Diagram illustrating the synaptic and extrasynaptic distributions of NMDARs and associated scaffolding and adhesion proteins, and especially the associations of extrasynaptic NMDARs with adjacent cell processes (see text for details). Although not discussed in this paper, note that other GluRs (AMPARs, kainate and delta iGluRs, and metabotropic GluRs [mGluRs]) are found at synapses and in extrasynaptic locations. AMPARs are typically the most abundant GluRs at synapses and may also be more common than NMDARs in extrasynaptic locations in some neurons. mGluRs are also widespread; some forms are particularly abundant in the perisynaptic zone. Like NMDARs, these GluRs also show close associations with other proteins that affect their trafficking and localization (not illustrated here). The arrangement of different GluRs such as AMPARs and NMDARs within the synapse has been studied but still is not well defined. And although some AMPARs and NMDARs may traffic together in neurons in early development [18], little is known about the association of these different types of GluRs in extrasynaptic locations. For reviews, see Gereau and Swanson [1], Lu and Roche [34], and MacGillavry et al. [35]. Diagram modified from Figure 9 of Petralia et al. [8].