Oxidant-dependent phosphorylation of p40phox in B lymphocytes.
As with the neutrophil NADPH oxidase, the B lymphocyte NADPH oxidase consists of a membrane-bound flavocytochrome b and regulatory factors including Rac and the cytosolic phox protein triad p67phox, p47phox, and p40phox. Here we demonstrate by phosphoamino acid analysis and the use of the potent PKC inhibitor GFX that, in response to stimulation of B lymphocytes with sodium orthovanadate and H(2)O(2), the p40phox component of the cytosolic phox triad is selectively phosphorylated on serine and threonine residues by a PKC-type protein kinase. The pattern of p40phox phosphorylation was closely related to the kinetics of tyrosine phosphorylation of PKC-delta, the main PKC isotype of B lymphocytes. Blocking H(2)O(2)-dependent tyrosine phosphorylation of PKC by genistein resulted in inhibition of p40phox phosphorylation. The correlation between the tyrosine phosphorylation of PKC-delta and the serine/threonine phosphorylation of p40phox, together with the inhibition of p40phox phosphorylation by rottlerin, a selective inhibitor of PKC-delta, makes the activated PKC-delta a likely candidate in the process of the oxidant-dependent phosphorylation of p40phox in B cells.
Grandvaux
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N
Laboratoire de Biochimie et Biophysique des Systèmes Intégrés (UMR 5092 CEA-CNRS-UJF), CEA-Grenoble, 17 avenue des martyrs, 38054 Grenoble Cedex 9, France.
Elsen
S
S
Vignais
P V
PV
D000098:Acetophenones / Q000494:pharmacology; D001402:B-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D001578:Benzopyrans / Q000494:pharmacology; D002458:Cell Fractionation; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D046911:Macromolecular Substances; D008301:Maleimides / Q000494:pharmacology; D019255:NADPH Oxidases / Q000737:chemistry / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051745:Protein Kinase C-delta; D014638:Vanadates / Q000494:pharmacology
D000098:Acetophenones; D001578:Benzopyrans; D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D046911:Macromolecular Substances; D008301:Maleimides; D016877:Oxidants; D010750:Phosphoproteins; C085072:neutrophil cytosol factor 40K; D014638:Vanadates; D006861:Hydrogen Peroxide; D019833:Genistein; C085746:rottlerin; D019255:NADPH Oxidases; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; C070515:bisindolylmaleimide I