Structural highlights
Function
[GRIA4_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 (By similarity).[1] [2] [3]
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
AMPA receptors (AMPARs) are tetrameric ligand-gated ion channels that couple the energy of glutamate binding to the opening of a transmembrane channel. Crystallographic and electrophysiological analysis of AMPARs has suggested a coupling between (1) cleft closure in the bilobate ligand-binding domain (LBD), (2) the resulting separation of transmembrane helix attachment points across subunit dimers, and (3) agonist efficacy. In general, more efficacious agonists induce greater degrees of cleft closure and transmembrane separation than partial agonists. Several apparent violations of the cleft-closure/efficacy paradigm have emerged, although in all cases, intradimer separation remains as the driving force for channel opening. Here, we examine the structural basis of partial agonism in GluA4 AMPARs. We find that the L651V substitution enhances the relative efficacy of kainate without increasing either LBD cleft closure or transmembrane separation. Instead, the conformational change relative to the wild-type:kainate complex involves a twisting motion with the efficacy contribution opposite from that expected based on previous analyses. As a result, channel opening may involve transmembrane rearrangements with a significant rotational component. Furthermore, a two-dimensional analysis of agonist-induced GluA2 LBD motions suggests that efficacy is not a linearly varying function of lobe 2 displacement vectors, but is rather determined by specific conformational requirements of the transmembrane domains.
Enhanced efficacy without further cleft closure: reevaluating twist as a source of agonist efficacy in AMPA receptors.,Birdsey-Benson A, Gill A, Henderson LP, Madden DR J Neurosci. 2010 Jan 27;30(4):1463-70. PMID:20107073[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Pasternack A, Coleman SK, Fethiere J, Madden DR, LeCaer JP, Rossier J, Pasternack M, Keinanen K. Characterization of the functional role of the N-glycans in the AMPA receptor ligand-binding domain. J Neurochem. 2003 Mar;84(5):1184-92. PMID:12603841
- ↑ Gill A, Birdsey-Benson A, Jones BL, Henderson LP, Madden DR. Correlating AMPA receptor activation and cleft closure across subunits: crystal structures of the GluR4 ligand-binding domain in complex with full and partial agonists. Biochemistry. 2008 Dec 30;47(52):13831-41. PMID:19102704 doi:10.1021/bi8013196
- ↑ Birdsey-Benson A, Gill A, Henderson LP, Madden DR. Enhanced efficacy without further cleft closure: reevaluating twist as a source of agonist efficacy in AMPA receptors. J Neurosci. 2010 Jan 27;30(4):1463-70. PMID:20107073 doi:30/4/1463
- ↑ Birdsey-Benson A, Gill A, Henderson LP, Madden DR. Enhanced efficacy without further cleft closure: reevaluating twist as a source of agonist efficacy in AMPA receptors. J Neurosci. 2010 Jan 27;30(4):1463-70. PMID:20107073 doi:30/4/1463
