Effect of guanine nucleotides on [3H] glutamate binding and on adenylate cyclase activity in rat brain membranes

Maribel A. Rubin, Alan C. Medeiros, Paula C.B. Rocha, Carolina B. Livi, Galo Ramirez, Diogo O. Souza

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

GMP-PNP, a non-hydrolyzable analog of GTP binds tightly to G-protein in the presence of Mg2+, so that the binding is stable even after exhaustive washings. This property was exploited to prepare membrane samples of rat brain where G-protein GTP-binding sites were saturated with GMP-PNP. Experiments carried out with these membranes showed that GTP, GMP-PNP, GDP-S and GMP (1 mM) inhibit the sodium-independent [3H]glutamate binding by 30-40% [F(4,40) = 5.9; p < .001], whereas only GMP-PNP activates adenylate cyclase activity [F(6,42) = 3.56; p < .01]. The inhibition of sodium-independent [3H]glutamate binding occurred in the absence of Mg2+. These findings suggest that guanine nucleotides may inhibit glutamate binding and activate adenylate cyclase through distinct mechanisms by acting on different sites.

Original languageEnglish (US)
Pages (from-to)181-187
Number of pages7
JournalNeurochemical Research
Volume22
Issue number2
DOIs
StatePublished - 1997
Externally publishedYes

Keywords

  • Adenylate cyclase
  • G-proteins
  • Glutamate
  • [H]glutamate-binding; guanine nucleotides

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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