Ionic regulation of glutamate binding sites

E. E. Mena, S. R. Whittemore, D. T. Monaghan, C. W. Cotman

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Cl- and Ca2+ increase glutamate binding to rat synaptic plasma membranes (SPMs) by revealing a distinct class of L-glutamate (L-Glu) binding sites. The present study was conducted to examine both the anion specificity of this response and the nature of the interaction between Cl- and Ca2+. Of the anions tested, Br- was the most effective in increasing the levels of L-Glu binding. Other effective anions were Cl-, NO3- and formate while F-, HCO3-CIO4-, propionate, SO42- and PO43- were ineffective. The anion specificity was similar to that observed for the Cl- membrane channel, suggesting that this binding site and the ion channel may be related. In the absence of Cl-, Ca2+ has little effect on L-Glu binding. Increasing the Cl- concentration increased the apparent affinity (decreased KCa2+) of the Ca2+-stimulated, L-Glu binding component and also decreased the maximal amount of the enhancement. Conversely, increasing Ca2+ levels increased the maximal enhancement of L-Glu binding brought about by Cl- without affecting the KCl- of the effect. Prior incubation of membranes with Ca2+ did not raise the level of L- Glu binding. Furthermore, EGTA was able to reverse the stimulation of L- Glu binding due to Ca2+. The results indicate that Ca2+ acts ionically to enhance L-Glu binding to rat SPMs.

Original languageEnglish (US)
Pages (from-to)2427-2433
Number of pages7
JournalLife Sciences
Issue number24
StatePublished - Dec 10 1984
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)


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