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7lep

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The composite LBD-TMD structure combined from all hippocampal AMPAR subtypes at 3.25 Angstrom resolution

Structural highlights

7lep is a 8 chain structure with sequence from Mus musculus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Electron Microscopy, Resolution 3.25Å
Ligands:	, , , , , ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

GRIA2_MOUSE Ionotropic glutamate receptor that functions as a ligand-gated cation channel, gated by L-glutamate and glutamatergic agonists such as alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), quisqualic acid, and kainic acid (By similarity). L-glutamate acts as an excitatory neurotransmitter at many synapses in the central nervous system and plays an important role in fast excitatory synaptic transmission (By similarity). Binding of the excitatory neurotransmitter L-glutamate induces a conformation change, leading to the opening of the cation channel, and thereby converts the chemical signal to an electrical impulse upon entry of monovalent and divalent cations such as sodium and calcium. The receptor then desensitizes rapidly and enters in a transient inactive state, characterized by the presence of bound agonist. In the presence of CACNG4 or CACNG7 or CACNG8, shows resensitization which is characterized by a delayed accumulation of current flux upon continued application of L-glutamate. Through complex formation with NSG1, GRIP1 and STX12 controls the intracellular fate of AMPAR and the endosomal sorting of the GRIA2 subunit toward recycling and membrane targeting (By similarity).[UniProtKB:P19491][UniProtKB:P42262]

Publication Abstract from PubMed

AMPA-selective glutamate receptors mediate the transduction of signals between the neuronal circuits of the hippocampus(1). The trafficking, localization, kinetics and pharmacology of AMPA receptors are tuned by an ensemble of auxiliary protein subunits, which are integral membrane proteins that associate with the receptor to yield bona fide receptor signalling complexes(2). Thus far, extensive studies of recombinant AMPA receptor-auxiliary subunit complexes using engineered protein constructs have not been able to faithfully elucidate the molecular architecture of hippocampal AMPA receptor complexes. Here we obtain mouse hippocampal, calcium-impermeable AMPA receptor complexes using immunoaffinity purification and use single-molecule fluorescence and cryo-electron microscopy experiments to elucidate three major AMPA receptor-auxiliary subunit complexes. The GluA1-GluA2, GluA1-GluA2-GluA3 and GluA2-GluA3 receptors are the predominant assemblies, with the auxiliary subunits TARP-gamma8 and CNIH2-SynDIG4 non-stochastically positioned at the B'/D' and A'/C' positions, respectively. We further demonstrate how the receptor-TARP-gamma8 stoichiometry explains the mechanism of and submaximal inhibition by a clinically relevant, brain-region-specific allosteric inhibitor.

Hippocampal AMPA receptor assemblies and mechanism of allosteric inhibition.,Yu J, Rao P, Clark S, Mitra J, Ha T, Gouaux E Nature. 2021 Jun;594(7863):448-453. doi: 10.1038/s41586-021-03540-0. Epub 2021 , May 12. PMID:33981040^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Yu J, Rao P, Clark S, Mitra J, Ha T, Gouaux E. Hippocampal AMPA receptor assemblies and mechanism of allosteric inhibition. Nature. 2021 Jun;594(7863):448-453. PMID:33981040 doi:10.1038/s41586-021-03540-0