5cc2
STRUCTURE OF THE LIGAND-BINDING DOMAIN OF THE IONOTROPIC GLUTAMATE RECEPTOR-LIKE GLUD2 IN COMPLEX WITH 7-CKA
Structural highlights
FunctionGRID2_RAT Receptor for glutamate. 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. Publication Abstract from PubMedThe GluD2 receptor is a fundamental component of postsynaptic sites in Purkinje neurons and is required for normal cerebellar function. GluD2 and the closely related GluD1 are classified as members of the ionotropic glutamate receptor (iGluR) super-family on basis of sequence similarity, but do not bind L-glutamate. The amino acid neurotransmitter D-serine (D-Ser) is a GluD2 receptor ligand, and endogenous D-Ser signaling through GluD2 has recently been shown to regulate endocytosis of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) type iGluRs during synaptic plasticity in the cerebellum such as long-term depression (LTD). Here, we investigate the pharmacology of the orthosteric binding site in GluD2 by examining the activity of analogs of D-Ser and GluN1 competitive antagonists at GluD2 receptors containing the lurcher mutation (GluD2LC), which promotes spontaneous channel activation. We identify several compounds that modulate GluD2LC, including a halogenated alanine analog as well as the kynurenic acid analog 7-chloro-4-oxo-1H-quinoline-2-carboxylic acid (7-chlorokynurenic acid; 7-CKA). By correlating thermodynamic and structural data for 7-CKA binding to the isolated GluD2 ligand binding domain (GluD2-LBD) using isothermal titration calorimetry (ITC) and X-ray protein crystallography, we find that binding of 7-CKA to GluD2-LBD differs from D-Ser by inducing an intermediate cleft-closure of the clamshell-shaped LBD. The GluD2 ligands identified here can potentially serve as a starting point for development of GluD2-selective ligands useful as tools in studies of the signaling role of the GluD2 receptor in the brain. Pharmacology and Structural Analysis of Ligand Binding to the Orthosteric Site of Glutamate-Like GluD2 Receptors.,Kristensen AS, Hansen KB, Naur P, Olsen L, Kurtkaya NL, Dravid SM, Kvist T, Yi F, Pohlsgaard J, Clausen RP, Gajhede M, Kastrup JS, Traynelis SF Mol Pharmacol. 2015 Dec 10. pii: mol.115.100909. PMID:26661043[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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