Figure 1.

Synaptic receptor trafficking pathways in neuronal dendrites. (A) Schematic representation of the secretory and endosomal trafficking pathway of postsynaptic receptors. Glutamate receptor subunits are assembled in the endoplasmic reticulcum (ER) and are transported via the Golgi apparatus to the synaptic plasma membrane. The interaction between receptor and motor proteins often occurs through motor adaptor/synaptic scaffolding proteins. (B) Model for the endosomal membrane trafficking machinery in dendrites. The internalization of AMPA receptors into endocytic vesicles is mediated by clathrin acting on the lateral membrane within the spine. Rab5 controls transport to early endosomes (also called sorting endosomes) whereas Rab4 and Rab11 are involved in the regulation of endosomal recycling back to the plasma membrane. Re-entry of internalized AMPAR into the Rab4-Rab11 endosomal recycling route requires GRASP-1.