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Wolfl J, Dagher MC, Fuchs A, Geiszt M, Ligeti E: In vitro activation of the NADPH oxidase by fluoride. Eur J Biochem. 1996 Jul 15;239(2):369-75.
Possible involvement of a factor activating GTP hydrolysis on Rac (Rac-GAP).. 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'-O-(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 of 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. |
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