In vitro activation of the NADPH oxidase by fluoride. Possible involvement of a factor activating GTP hydrolysis on Pac (Rac-GAP)

Jutta Wölfl, Marie Claire Dagher, Alexandra Fuchs, Miklós Geiszt, Erzsébet Ligeti

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Abstract

The possible mechanism of activation of the NADPH oxidase by fluoride was investigated in the cell-free system. It is shown that the stimulatory effect of fluoride is inhibited by guanosine 5'-0-(2-thiodiphosphate) (GDP[S]) and potentiated by GTP. The effect of fluoride is not additive with GTP[S]. Fluoride activation requires the presence of Mg2+ in millimolar concentration but is independent of Al3+. The activating effect of fluoride is preserved in solubilized membrane extract after removal of the majority of heterotrimeric GTP-binding proteins by immunoadsorption. Fluoride has no direct action either on the nucleotide exchange or GTP hydrolysis of the isolated Rac protein. In contrast, fluoride effectively inhibits Rac-GTPase activity enhanced by a membrane component. In this way, fluoride could prolong the prevalence of Rac in the GTP-bound state and, as a consequence, activate NADPH oxidase; The possibility of the involvement of a membrane-bound Rac GTPase-activating protein activity in the physiological regulation of the enzyme is raised.

Original languageEnglish
Pages (from-to)369-375
Number of pages7
JournalEuropean Journal of Biochemistry
Volume239
Issue number2
DOIs
Publication statusPublished - Jan 1 1996

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Keywords

  • Fluoride
  • GTP-binding proteins
  • NADPH oxidase
  • Neutrophil granulocytes
  • Rac-GTPase-activating protein

ASJC Scopus subject areas

  • Biochemistry

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