Open AccessIn vitro Activation of the NADPH Oxidase by Fluoride
Author(s) -
Wölfl Jutta,
Dagher MarieClaire,
Fuchs Alexandra,
Geiszt Miklós,
Ligeti Erzsébet
Publication year - 1996
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1996.0369u.x
Subject(s) - gtp' , fluoride , chemistry , gtpase , guanosine , g protein , nadph oxidase , enzyme , biochemistry , heterotrimeric g protein , membrane , biophysics , biology , signal transduction , inorganic chemistry
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 Mg 2+ in millimolar concentration but is independent of Al 3+ . 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.