RT Journal Article
SR Electronic
T1 Quinazolone-Alkyl-Carboxylic Acid Derivatives Inhibit Transmembrane Ca<sup>2+</sup> Ion Flux to (+)-(<em>S</em>)-α-Amino-3-hydroxy-5-methylisoxazole-4-propionic Acid
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 920
OP 928
DO 10.1124/mol.59.4.920
VO 59
IS 4
A1 Éva Szárics
A1 Lajos Nyikos
A1 Péter Barabás
A1 Ilona Kovács
A1 Nina Skuban
A1 Eszter Temesváriné-Major
A1 Orsolya Egyed
A1 Peter I. Nagy
A1 József Kökösi
A1 Krisztina Takács-Novák
A1 Julianna Kardos
YR 2001
UL http://molpharm.aspetjournals.org/content/59/4/920.abstract
AB Comparison of the kinetics of the inward Ca2+ ion flux to (S)-α-Amino-3-hydroxy-5-methylisoxazole-4-propionic acid [(S)-AMPA] in cerebrocortical homogenates and that of the previously reported transmembrane Na+ ion influx mediated by an AMPA receptor in hippocampal homogenates established that the agonist-induced opening of the AMPA receptor channels occurs in two kinetically distinguishable phases. Here we report that the 2-methyl-4-oxo-3H-quinazoline-3-acetic acid (Q1) inhibits the major slow-phase response specifically, whereas the acetyl piperidine derivative (Q5) is a more potent inhibitor of the fast-phase response. Both the quinazolone-3-propionic acid (Q2) and the quinazolone-3-acetic acid methyl ester (Q3) enhanced the slow-phase response to (S)-AMPA. The information provided by docking different Q1, Q2, and Q5 models at the ligand-binding core of iGluRs were used to define agonistic and antagonistic modes of interactions. Based on the effects of quinazolone-3-alkyl-carboxylic acid derivatives on specific [3H]Glu binding and kinetically distinguishable Ca2+ ion permeability responses to (S)-AMPA and molecular modeling, the fast- and the slow-phase (S)-AMPA-elicited Ca2+ ion fluxes were corresponded to different subunit compositions and degrees of S1S2 bridging interaction relative to substitution of kainate thereupon. Substitutions of agonists and antagonists into the iGluR2 S1S2 ligand binding core induced different modes of domain-domain bridging.