4g8n | pdb_00004g8n
Crystal structure of the kainate receptor GluK3 ligand-binding domain in complex with the agonist G8M
Structural highlights
FunctionGRIK3_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. The postsynaptic actions of Glu are mediated by a variety of receptors that are named according to their selective agonists. This receptor binds domoate > kainate >> L-glutamate = quisqualate >> AMPA = NMDA.[1] Publication Abstract from PubMedConformationally restricted glutamate analogues have been pharmacologically characterized at AMPA and kainate receptors and the crystal structures have been solved of the ligand (2S,1'R,2'S)-2-(2'-carboxycyclobutyl)glycine (CBG-IV) in complex with the ligand binding domains of the AMPA receptor GluA2 and the kainate receptor GluK3. These structures show that CBG-IV interacts with the binding pocket in the same way as (S)-glutamate. The binding affinities reveal that CBG-IV has high affinity at the AMPA and kainate receptor subtypes. Appreciable binding affinity of CBG-IV was not observed at NMDA receptors, where the introduction of the carbocyclic ring is expected to lead to a steric clash with binding site residues. CBG-IV was demonstrated to be an agonist at both GluA2 and the kainate receptor GluK1. CBG-IV showed high affinity binding to GluK1 compared to GluA2, GluK2 and GluK3, which exhibited lower affinity for CBG-IV. The structure of GluA2 LBD and GluK3 LBD in complex with CBG-IV revealed similar binding site interactions to those of (S)-glutamate. No major conformational rearrangements compared to the (S)-glutamate bound conformation were found in GluK3 in order to accommodate CBG-IV, in contrast with GluA2 where a shift in lobe D2 binding site residues occurs, leading to an increased binding cavity volume compared to the (S)-glutamate bound structure. Pharmacological and structural characterization of conformationally restricted (S)-glutamate analogues at ionotropic glutamate receptors.,Juknaite L, Venskutonyte R, Assaf Z, Faure S, Gefflaut T, Aitken DJ, Nielsen B, Gajhede M, Kastrup JS, Bunch L, Frydenvang K, Pickering DS J Struct Biol. 2012 Jul 9. PMID:22789682[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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