1. A rise in ionized calcium activates the neutrophil NADPH-oxidase but is not sufficient to directly translocate cytosolic p47phox or p67phox to b cytochrome containing membranes.
- Author
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Movitz C, Sjölin C, and Dahlgren C
- Subjects
- Annexin A1 metabolism, Biological Transport, Active, Cytochrome b Group metabolism, Cytosol metabolism, Enzyme Activation drug effects, Humans, In Vitro Techniques, Intracellular Membranes metabolism, Ionomycin pharmacology, Ionophores pharmacology, Neutrophils drug effects, Phosphoproteins metabolism, Reactive Oxygen Species metabolism, Subcellular Fractions metabolism, Calcium metabolism, NADPH Oxidases metabolism, Neutrophils metabolism
- Abstract
Neutrophil production of reactive oxygen species is dependent on an assembly process that involves a translocation of the cytosolic NADPH-oxidase components (p47phox; p67phox; Rac2) to a b cytochrome containing membrane. Based on the fact that an intracellular Ca2+ rise can activate the oxidase without any extracellular release of reactive oxygen species, we suggest that the oxidase can be assembled in a membrane distinct from the plasma membrane. Disintegrated cells were used to monitor Ca2+ dependent membrane binding of neutrophil cytosolic proteins. Membranes containing the b cytochrome part of the oxidase, i.e., specific granules and plasma membranes/secretory vesicles, were used in the translocation experiments. Several cytosolic proteins were found to translocate to specific granules as well as the plasma membranes/secretory vesicles, one of them being annexin I. Using antibodies in the blotting assay against the cytosolic oxidase components p47phox and p67phox, we could show that no Ca2+ dependent translocation of these cytosolic proteins occur to neither of the b cytochrome containing membranes.
- Published
- 1997
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