Related Experiment Video
Updated: Aug 21, 2026

Modeling Ligands into Maps Derived from Electron Cryomicroscopy
Published on: July 19, 2024
The Three-dimensional Structure of an Ionotropic Glutamate Receptor Reveals a Dimer-of-dimers Assembly
Willem Tichelaar1, Markus Safferling, Kari Keinänen
1Ion Channel Structure Group, Max Planck Institute for Medical Research, Jahnstr. 29, D-69120 Heidelberg, Germany.
Abstract:
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 approximately 20A 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 approximately 170Ax140Ax110A, 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.
Related Concept Videos
Ligand-Gated Ion Channel Receptor: Gating Mechanism
Ligand-gated Ion Channels
Three Subfamilies of Ligand-gated Ion Channels
Ligand-gated ion channels fall into three subfamilies. The 'Cys-loop' includes the nicotinic acetylcholine receptors, γ-aminobutyric acid (GABA), glycine, and 5-hydroxytryptamine receptors. The second one is the 'Pore-loop' channels that include the...
Assembly of Signaling Complexes
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
Ligand Binding Sites
Protein-ligand interactions are quite specific; even though numerous potential ligands surround a cellular protein at any given time, only a particular ligand can bind to that protein. Moreover, a ligand binds only to a dedicated area on the surface of the protein, known as the...
Structure of Cadherins
G-protein Coupled Receptors

