Abstract
Fluoride activation of the cGMP cascade of vision requires the presence of aluminum, and is shown to be mediated by the binding of one A1F-4 to the GDP/GTP-binding subunit of transducin. The presence of GDP in the site is required: A1F-4 is ineffective when the site is empty or when GDP beta S is substituted for GDP. This sensitivity to the sulfur of GDP beta S suggests that A1F-4 is in contact with the GDP. Striking structural similarities between A1F-4 and PO3-4 lead us to propose that A1F-4 mimics the role of the gamma-phosphate of GTP.
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Predominant contribution of the G protein-mediated mechanism to NaF-induced vascular contractions in diabetic rats: association with an increased level of G(qalpha) expression.
The purpose of this study was to determine the mechanism responsible for alterations in NaF-induced contractions of blood vessels from streptozotocin-induced diabetic rats. In the presence of AlCl(3), NaF (>/=7.5 mM) produced significantly greater contractions in diabetic aorta and mesenteric artery compared with age-matched controls. Pretreatment with 1 microM nifedipine
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Fluoride complexes of aluminium or beryllium act on G-proteins as reversibly bound analogues of the gamma phosphate of GTP.
Fluoride activation of G proteins requires the presence of aluminium or beryllium and it has been suggested that AIF4- acts as an analogue of the gamma-phosphate of GTP in the nucleotide site. We have investigated the action of AIF4- or of BeF3- on transducin (T), the G protein of the
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Paradoxes of fluoride toxicity
Numerous literature sources reveal evidence that fluoride affects the activities of numerous enzymes in vitro as well as in vivo. Millions of people live in endemic fluoride areas with a severe public health problem. A plethora of data suggest that fluoride should be recognized as a developmental neurotoxicant for humans.
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Mechanism of toxic action of fluoride in dental fluorosis: whether trimeric G proteins participate in the disturbance of intracellular transport of secretory ameloblast exposed to fluoride.
In enamel fluorosis model rats treated with sodium fluoride, secretory ameloblasts of incisor tooth germs exhibited disruption of intracellular trafficking. We examined whether heterotrimeric G proteins participated in the disruption of vesicular trafficking of the secretory ameloblast exposed to fluoride, using immunoblotting and pertussis toxin (IAP)-induced adenosyl diphosphate (ADP)-ribosylation for
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Heterotrimeric G proteins as fluoride targets in bone (review).
Fluoride is an acknowledged bone anabolic agent. Nevertheless, a narrow therapeutic window and the adverse effects at higher therapeutic doses prevent broad clinical application of fluoride for treatment of diseases of bone loss, such as osteoporosis. The cellular and molecular mechanisms of fluoride action are poorly understood. Recent advances in
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