Non-NMDA glutamate receptor antagonist 3H-CNOX binds with equal affinity to two agonist states of quisqualate receptors.

Article date: 1989/10/1

PubMed ID: 2573355

Journal name: Biochemical pharmacology (ISSN: 0006-2952)


Binding of 3H-CNQX to rat cortical membranes is saturable and reversible. Apparently, 3H-CNQX binds to a single site with KD = 39 nM. However, studies using AMPA as inhibitor revealed a biphasic inhibition of 3H-CNQX binding. The results suggest that CNQX binds with the same affinity to two different sites. The molecular target size of 3H-CNQX binding (51.8 +/- 3.4 kD) is equivalent to the size of the high affinity 3H-AMPA binding sites, but different from the high affinity 3H-kainate binding sites. A monoexponential decay curve for the high energy radiation inactivation analysis of 3H-CNQX binding indicates that the two 3H-CNQX binding sites have the same molecular weight and therefore might be two different conformations of the same receptor. The standard excitatory amino acids quisqualate, AMPA and kainate have a different rank order of potency as binding inhibitors at the two conformations of the quisqualate receptor.

Author List: Honore T, Drejeŕ J, Nielsen E O, Nielsen M

Publication Types: Journal Article

Substances mentioned in the article: Glutamates; Oxadiazoles; Quinoxalines; Receptors, AMPA; Receptors, Glutamate; Receptors, Kainic Acid; Receptors, Neurotransmitter; Ibotenic Acid; 6-Cyano-7-nitroquinoxaline-2,3-dione; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid;

Mesh terms: 6-Cyano-7-nitroquinoxaline-2,3-dione; Animals; Binding Sites; Cerebral Cortex/metabolism; Glutamates/metabolism; Ibotenic Acid/analogs & derivatives; In Vitro Techniques; Molecular Weight; Oxadiazoles/metabolism; Protein Conformation; Quinoxalines/metabolism; Rats; Receptors, AMPA; Receptors, Glutamate; Receptors, Kainic Acid; Receptors, Neurotransmitter/metabolism; Temperature; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid;

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