| 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 receptors are the major excitatory neurotransmitter receptors in the CNS and are involved in numerous neurological disorders. An agonist-binding site is present in each of four subunits that form a functional channel. Binding consists of three steps: docking of agonist to the bi-lobed ligand binding domain (LBD), closure of the LBD, and increased stability of the closed-lobe conformation through interlobe hydrogen bonding. We describe GluA3 single channel currents activated by nitrowillardiine (NO(2)W) and chlorowillardiine (ClW) in the presence of cyclothiazide, in conjunction with crystal structures of GluA2 and GluA3 LBDs bound to fluorowillardiine (FW), ClW, and NO(2)W. When bound to NO(2)W or ClW, the GluA3 channel opens to three conductance levels with comparable open probabilities and displays modal behavior similar to that obtained with glutamate and FW as agonists (Poon et al., 2010). At lower concentrations, ClW evoked an alternate kinetic behavior, consisting of high open probability in lower conductance states. The structure of ClW bound to GluA3 LBD exhibits a unique partially open hydrogen bonding structure that may be associated with these alternative kinetics. NO(2)W evoked longer open times than seen for other agonists in high and very high modes. The structure of GluA2 LBD bound to NO2W exhibits fully closed lobes with additional interlobe interactions mediated by the nitro group. Beyond differences in efficacy between full and partial agonists, the complexities of the single channel behavior of AMPA receptors may also be associated with small interactions that modify the stability of various degrees of closure.
Mechanisms of Modal Activation of GluA3 Receptors.,Poon K, Ahmed AH, Nowak LM, Oswald RE Mol Pharmacol. 2011 Apr 4. PMID:21464198[15]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
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- ↑ 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
- ↑ Poon K, Ahmed AH, Nowak LM, Oswald RE. Mechanisms of Modal Activation of GluA3 Receptors. Mol Pharmacol. 2011 Apr 4. PMID:21464198 doi:10.1124/mol.111.071688
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