The three-dimensional structure of an ionotropic glutamate receptor reveals a dimer-of-dimers assembly

[摘要] The ionotropic glutamate receptors (iGluRs) represent a major family of ion channels whose quaternary structure has not yet been defined. Here, we present the three-dimensional structure of a fully assembled iGluR determined at similar to20 Angstrom resolution by electron microscopy. Analysis of negatively stained single-particle images reveals the presence of 2-fold, but not 4-fold, symmetry for these tetrameric channels, providing the first direct structural evidence for a dimer-of-dimers assembly. The receptor appears elongated, measuring similar to170 Angstrom x 140 Angstrom x 110 Angstrom, with the 2-fold symmetry centered on its longitudinal axis. The overall molecular shape and symmetry suggest an orientation relative to the membrane and permit the identification of a putative transmembrane domain. Internal cavities located along the longitudinal axis may represent components of the ion conduction pathway. (C) 2004 Elsevier Ltd. All rights reserved.

[发布日期] 2004-11-19

[关键词] ionotropic glutamate receptor;AMPA receptor;GluRB;ion channel gating;electron microscopy