6I53

Cryo-EM structure of the human synaptic alpha1-beta3-gamma2 GABAA receptor in complex with Megabody38 in a lipid nanodisc

Summary for 6I53

• Entry DOI: 10.2210/pdb6i53/pdb
• EMDB information: 4411
• Descriptor: Gamma-aminobutyric acid receptor subunit beta-3, [(2R)-2-octanoyloxy-3-[oxidanyl-[(1R,2R,3S,4R,5R,6S)-2,3,6-tris(oxidanyl)-4,5-diphosphonooxy-cyclohexyl]oxy-phosphoryl]oxy-propyl] octanoate, Gamma-aminobutyric acid receptor subunit alpha-1, ... (10 entities in total)
• Functional Keywords: ligand gated ion channel cys-loop receptor gaba-a receptor, transport protein
• Biological source: Homo sapiens (Human); More
• Total number of polymer chains: 6
• Total formula weight: 294283.60

Authors

Laverty, D.,Desai, R.,Uchanski, T.,Masiulis, S.,Wojciech, J.S.,Malinauskas, T.,Zivanov, J.,Pardon, E.,Steyaert, J.,Miller, K.W.,Aricescu, A.R. (deposition date: 2018-11-12, release date: 2019-01-02, Last modification date: 2024-10-23)

Primary citation

Laverty, D.,Desai, R.,Uchanski, T.,Masiulis, S.,Stec, W.J.,Malinauskas, T.,Zivanov, J.,Pardon, E.,Steyaert, J.,Miller, K.W.,Aricescu, A.R.
Cryo-EM structure of the human alpha 1 beta 3 gamma 2 GABAAreceptor in a lipid bilayer.
Nature, 565:516-520, 2019

PubMed Abstract: Type A γ-aminobutyric acid (GABA) receptors are pentameric ligand-gated ion channels and the main drivers of fast inhibitory neurotransmission in the vertebrate nervous system. Their dysfunction is implicated in a range of neurological disorders, including depression, epilepsy and schizophrenia. Among the numerous assemblies that are theoretically possible, the most prevalent in the brain are the α1β2/3γ2 GABA receptors. The β3 subunit has an important role in maintaining inhibitory tone, and the expression of this subunit alone is sufficient to rescue inhibitory synaptic transmission in β1-β3 triple knockout neurons. So far, efforts to generate accurate structural models for heteromeric GABA receptors have been hampered by the use of engineered receptors and the presence of detergents. Notably, some recent cryo-electron microscopy reconstructions have reported 'collapsed' conformations; however, these disagree with the structure of the prototypical pentameric ligand-gated ion channel the Torpedo nicotinic acetylcholine receptor, the large body of structural work on homologous homopentameric receptor variants and the logic of an ion-channel architecture. Here we present a high-resolution cryo-electron microscopy structure of the full-length human α1β3γ2L-a major synaptic GABA receptor isoform-that is functionally reconstituted in lipid nanodiscs. The receptor is bound to a positive allosteric modulator 'megabody' and is in a desensitized conformation. Each GABA receptor pentamer contains two phosphatidylinositol-4,5-bisphosphate molecules, the head groups of which occupy positively charged pockets in the intracellular juxtamembrane regions of α1 subunits. Beyond this level, the intracellular M3-M4 loops are largely disordered, possibly because interacting post-synaptic proteins are not present. This structure illustrates the molecular principles of heteromeric GABA receptor organization and provides a reference framework for future mechanistic investigations of GABAergic signalling and pharmacology.

PubMed: 30602789
DOI: 10.1038/s41586-018-0833-4

Experimental method

ELECTRON MICROSCOPY (3.2 Å)