Crystal structure and association behaviour of the GluR2 amino-terminal domain.

Fast excitatory neurotransmission is mediated largely by ionotropic glutamate receptors (iGluRs), tetrameric, ligand-gated ion channel proteins comprised of three subfamilies, AMPA, kainate and NMDA receptors, with each subfamily sharing a common, modular-domain architecture. For all receptor subfamilies, active channels are exclusively formed by assemblages of subunits within the same subfamily, a molecular process principally encoded by the amino-terminal domain (ATD). However, the molecular basis by which the ATD guides subfamily-specific receptor assembly is not known. Here we show that AMPA receptor GluR1- and GluR2-ATDs form tightly associated dimers and, by the analysis of crystal structures of the GluR2-ATD, propose mechanisms by which the ATD guides subfamily-specific receptor assembly.