Subcellular localization and dynamics of components of the respiratory burst oxidase.
Membrane and cytosolic factors cooperate to generate NADPH-oxidase. The study of the syndrome of NADPH-oxidase deficiencies, chronic granulomatous disease, has enabled the identification of two membrane factors: a flavin adenine dinucleotide flavoprotein and a b cytochrome. The nature of the cytosolic components is still unknown, but a 47-kD protein, whose phosphorylation occurs in parallel with the generation of a respiratory burst in intact cells, seems to be one of the cytosolic factors. The subcellular localization of the membrane-bound NADPH-oxidase components has been studied in neutrophils: In unstimulated cells, only a minute fraction of the NADPH-oxidase components is localized in the plasma membrane, whereas approximately 80% is localized in the membrane of the specific granules and the majority of the rest is in a newly described membrane-bound compartment, the secretory granules, identified by latent alkaline phosphatase. During stimulation, these NADPH-oxidase components are translocated to the plasma membrane as a result of fusion of granule membrane with plasma membrane. Only the NADPH-oxidase components present in the plasma membrane are incorporated in the respiratory burst oxidase generated in intact cells.
Borregaard
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Department of Internal Medicine and Hematology A, University Hospital, Copenhagen, Denmark.
D000818:Animals; D006801:Humans; D009247:NADH, NADPH Oxidoreductases / Q000097:blood*; D019255:NADPH Oxidases; D009504:Neutrophils / Q000201:enzymology*; D013347:Subcellular Fractions / Q000201:enzymology; D013481:Superoxides / Q000097:blood*
D013481:Superoxides; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C022709:superoxide-forming enzyme