| Structural highlights
Function
GRIA2_RAT Receptor for glutamate that functions as ligand-gated ion channel in the central nervous system and plays an important role in excitatory synaptic transmission. L-glutamate acts as an excitatory neurotransmitter at many synapses in the central nervous system. 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. The receptor then desensitizes rapidly and enters 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 glutamate.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
Publication Abstract from PubMed
AMPA glutamate receptors (AMPARs), the primary mediators of excitatory neurotransmission in the brain, are either GluA2 subunit-containing and thus Ca(2+)-impermeable, or GluA2-lacking and Ca(2+)-permeable(1). Despite their prominent expression throughout interneurons and glia, their role in long-term potentiation and their involvement in a range of neuropathologies(2), structural information for GluA2-lacking receptors is currently absent. Here we determine and characterize cryo-electron microscopy structures of the GluA1 homotetramer, fully occupied with TARPgamma3 auxiliary subunits (GluA1/gamma3). The gating core of both resting and open-state GluA1/gamma3 closely resembles GluA2-containing receptors. However, the sequence-diverse N-terminal domains (NTDs) give rise to a highly mobile assembly, enabling domain swapping and subunit re-alignments in the ligand-binding domain tier that are pronounced in desensitized states. These transitions underlie the unique kinetic properties of GluA1. A GluA2 mutant (F231A) increasing NTD dynamics phenocopies this behaviour, and exhibits reduced synaptic responses, reflecting the anchoring function of the AMPAR NTD at the synapse. Together, this work underscores how the subunit-diverse NTDs determine subunit arrangement, gating properties and ultimately synaptic signalling efficiency among AMPAR subtypes.
Structural mobility tunes signalling of the GluA1 AMPA glutamate receptor.,Zhang D, Ivica J, Krieger JM, Ho H, Yamashita K, Stockwell I, Baradaran R, Cais O, Greger IH Nature. 2023 Sep;621(7980):877-882. doi: 10.1038/s41586-023-06528-0. Epub 2023 , Sep 13. PMID:37704721[15]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
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- ↑ Jin R, Horning M, Mayer ML, Gouaux E. Mechanism of activation and selectivity in a ligand-gated ion channel: structural and functional studies of GluR2 and quisqualate. Biochemistry. 2002 Dec 31;41(52):15635-43. PMID:12501192
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- ↑ Armstrong N, Mayer M, Gouaux E. Tuning activation of the AMPA-sensitive GluR2 ion channel by genetic adjustment of agonist-induced conformational changes. Proc Natl Acad Sci U S A. 2003 May 13;100(10):5736-41. Epub 2003 May 2. PMID:12730367 doi:http://dx.doi.org/10.1073/pnas.1037393100
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- ↑ Frandsen A, Pickering DS, Vestergaard B, Kasper C, Nielsen BB, Greenwood JR, Campiani G, Fattorusso C, Gajhede M, Schousboe A, Kastrup JS. Tyr702 is an important determinant of agonist binding and domain closure of the ligand-binding core of GluR2. Mol Pharmacol. 2005 Mar;67(3):703-13. Epub 2004 Dec 9. PMID:15591246 doi:10.1124/mol.104.002931
- ↑ Armstrong N, Jasti J, Beich-Frandsen M, Gouaux E. Measurement of conformational changes accompanying desensitization in an ionotropic glutamate receptor. Cell. 2006 Oct 6;127(1):85-97. PMID:17018279 doi:10.1016/j.cell.2006.08.037
- ↑ Kasper C, Pickering DS, Mirza O, Olsen L, Kristensen AS, Greenwood JR, Liljefors T, Schousboe A, Watjen F, Gajhede M, Sigurskjold BW, Kastrup JS. The structure of a mixed GluR2 ligand-binding core dimer in complex with (S)-glutamate and the antagonist (S)-NS1209. J Mol Biol. 2006 Apr 7;357(4):1184-201. Epub 2006 Jan 31. PMID:16483599 doi:10.1016/j.jmb.2006.01.024
- ↑ Sobolevsky AI, Rosconi MP, Gouaux E. X-ray structure, symmetry and mechanism of an AMPA-subtype glutamate receptor. Nature. 2009 Dec 10;462(7274):745-56. Epub . PMID:19946266 doi:10.1038/nature08624
- ↑ Rossmann M, Sukumaran M, Penn AC, Veprintsev DB, Babu MM, Greger IH. Subunit-selective N-terminal domain associations organize the formation of AMPA receptor heteromers. EMBO J. 2011 Mar 2;30(5):959-71. Epub 2011 Feb 11. PMID:21317873 doi:10.1038/emboj.2011.16
- ↑ Ahmed AH, Wang S, Chuang HH, Oswald RE. Mechanism of AMPA receptor activation by partial agonists: disulfide trapping of closed lobe conformations. J Biol Chem. 2011 Aug 16. PMID:21846932 doi:10.1074/jbc.M111.269001
- ↑ Zhang D, Ivica J, Krieger JM, Ho H, Yamashita K, Stockwell I, Baradaran R, Cais O, Greger IH. Structural mobility tunes signalling of the GluA1 AMPA glutamate receptor. Nature. 2023 Sep;621(7980):877-882. PMID:37704721 doi:10.1038/s41586-023-06528-0
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