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Structure of the human GluN1/GluN2A NMDA receptor in the glutamate/glycine-bound state at pH 7.8
Structural highlights
DiseaseNMDE1_HUMAN Landau-Kleffner syndrome;Early-onset epileptic encephalopathy and intellectual disability due to GRIN2A mutation;Continuous spikes and waves during sleep;Rolandic epilepsy;Rolandic epilepsy - speech dyspraxia. The disease is caused by mutations affecting the gene represented in this entry. A chromosomal aberration involving GRIN2A has been found in a family with epilepsy and neurodevelopmental defects. Translocation t(16;17)(p13.2;q11.2). GRIN2A somatic mutations have been frequently found in cutaneous malignant melanoma, suggesting that the glutamate signaling pathway may play a role in the pathogenesis of melanoma.[1] [2] FunctionNMDE1_HUMAN NMDA receptor subtype of glutamate-gated ion channels possesses high calcium permeability and voltage-dependent sensitivity to magnesium. Activation requires binding of agonist to both types of subunits. Publication Abstract from PubMedN-methyl-D-aspartate (NMDA) receptors are critical for synaptic development and plasticity. While glutamate is the primary agonist, protons can modulate NMDA receptor activity at synapses during vesicle exocytosis by mechanisms that are unknown. We used cryo-electron microscopy to solve the structures of the human GluN1-GluN2A NMDA receptor at pH 7.8 and pH 6.3. Our structures demonstrate that the proton sensor predominantly resides in the N-terminal domain (NTD) of the GluN2A subunit and reveal the allosteric coupling mechanism between the proton sensor and the channel gate. Under high-pH conditions, the GluN2A-NTD adopts an "open-and-twisted" conformation. However, upon protonation at the lower pH, the GluN2A-NTD transits from an open- to closed-cleft conformation, causing rearrangements between the tetrameric NTDs and agonist-binding domains. The conformational mobility observed in our structures (presumably from protonation) is supported by molecular dynamics simulation. Our findings reveal the structural mechanisms by which protons allosterically inhibit human GluN1-GluN2A receptor activity. Structural Basis of the Proton Sensitivity of Human GluN1-GluN2A NMDA Receptors.,Zhang JB, Chang S, Xu P, Miao M, Wu H, Zhang Y, Zhang T, Wang H, Zhang J, Xie C, Song N, Luo C, Zhang X, Zhu S Cell Rep. 2018 Dec 26;25(13):3582-3590.e4. doi: 10.1016/j.celrep.2018.11.071. PMID:30590034[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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