| Structural highlights
3h6t is a 3 chain structure with sequence from Rattus norvegicus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Method: | X-ray diffraction, Resolution 2.25Å |
| Ligands: | , , , , , , |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT |
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]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Ionotropic glutamate receptors (iGluRs) mediate fast excitatory neurotransmission. Upon glutamate application, 2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid receptors undergo rapid and almost complete desensitization that can be attenuated by positive allosteric modulators. The molecular mechanism of positive allosteric modulation has been elucidated previously by crystal structures of the ligand-binding core of iGluR2 in complex with, for example, cyclothiazide (CTZ). Here, we investigate the structure and function of CTZ and three closely related analogues NS1493, NS5206, and NS5217 at iGluR2, by X-ray crystallography and fast application patch-clamp electrophysiology. CTZ was the most efficacious and potent modulator of the four compounds on iGluR2(Q)(i) [E(max) normalized to response of glutamate: 754% (CTZ), 490% (NS1493), 399% (NS5206), and 476% (NS5217) and EC(50) in micromolar: 10 (CTZ), 26 (NS1493), 43 (NS5206), and 48 (NS5217)]. The four modulators divide into three groups according to efficacy and desensitization kinetics: (1) CTZ increases the peak current efficacy twice as much as the three analogues and nearly completely blocks receptor desensitization; (2) NS5206 and NS5217 have low efficacy and only attenuate desensitization partially; (3) NS1493 has low efficacy but nearly completely blocks receptor desensitization. A hydrophobic substituent at the 3-position of the 1,1-dioxo-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine ring system is important for compound efficacy, with the following ranking: norbornenyl (bicyclo[2.2.1]hept-2-ene)>cyclopentyl>methyl. The replacement of the norbornenyl moiety with a significantly less hydrophobic cyclopentane ring increases the flexibility of the modulator as the cyclopentane ring adopts various conformations at the iGluR2 allosteric binding site. The main structural feature responsible for a nearly complete block of desensitization is the presence of an NH hydrogen bond donor in the 4-position of the 1,1-dioxo-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine ring system, forming an anchoring hydrogen bond to Ser754. Therefore, the atom at the 4-position of CTZ seems to be a major determinant of receptor desensitization kinetics.
Distinct structural features of cyclothiazide are responsible for effects on peak current amplitude and desensitization kinetics at iGluR2.,Hald H, Ahring PK, Timmermann DB, Liljefors T, Gajhede M, Kastrup JS J Mol Biol. 2009 Sep 4;391(5):906-17. Epub 2009 Jul 8. PMID:19591837[15]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
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- ↑ Schwenk J, Harmel N, Zolles G, Bildl W, Kulik A, Heimrich B, Chisaka O, Jonas P, Schulte U, Fakler B, Klocker N. Functional proteomics identify cornichon proteins as auxiliary subunits of AMPA receptors. Science. 2009 Mar 6;323(5919):1313-9. doi: 10.1126/science.1167852. PMID:19265014 doi:10.1126/science.1167852
- ↑ Kato AS, Gill MB, Ho MT, Yu H, Tu Y, Siuda ER, Wang H, Qian YW, Nisenbaum ES, Tomita S, Bredt DS. Hippocampal AMPA receptor gating controlled by both TARP and cornichon proteins. Neuron. 2010 Dec 22;68(6):1082-96. doi: 10.1016/j.neuron.2010.11.026. PMID:21172611 doi:10.1016/j.neuron.2010.11.026
- ↑ 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
- ↑ Sun Y, Olson R, Horning M, Armstrong N, Mayer M, Gouaux E. Mechanism of glutamate receptor desensitization. Nature. 2002 May 16;417(6886):245-53. PMID:12015593 doi:10.1038/417245a
- ↑ Jin R, Banke TG, Mayer ML, Traynelis SF, Gouaux E. Structural basis for partial agonist action at ionotropic glutamate receptors. Nat Neurosci. 2003 Aug;6(8):803-10. PMID:12872125 doi:10.1038/nn1091
- ↑ 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
- ↑ Jin R, Clark S, Weeks AM, Dudman JT, Gouaux E, Partin KM. Mechanism of positive allosteric modulators acting on AMPA receptors. J Neurosci. 2005 Sep 28;25(39):9027-36. PMID:16192394 doi:25/39/9027
- ↑ 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
- ↑ Hald H, Ahring PK, Timmermann DB, Liljefors T, Gajhede M, Kastrup JS. Distinct structural features of cyclothiazide are responsible for effects on peak current amplitude and desensitization kinetics at iGluR2. J Mol Biol. 2009 Sep 4;391(5):906-17. Epub 2009 Jul 8. PMID:19591837 doi:10.1016/j.jmb.2009.07.002
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