Phosphorylation of p40-phox during activation of neutrophil NADPH oxidase.
NADPH oxidase, a superoxide-producing enzyme in phagocytic cells, consists of membrane-associated cytochrome b558 and cytosolic components (p47-phox, p67-phox, p40-phox, rac 1/2). Activation of NADPH oxidase is accompanied by the phosphorylation of cytosolic components (p47-phox and p67-phox). In this study, we have examined whether p40-phox, a newly identified cytosolic component, is phosphorylated during neutrophil activation, and the relationship between p40-phox phosphorylation and NADPH oxidase activation. When 32P-labeled guinea pig neutrophils were stimulated by phorbol 12-myristate 13-acetate, p40-phox was phosphorylated as p47-phox. It is interesting that phosphorylation of p40-phox was markedly inhibited by protein kinase C inhibitor, H-7, but not by casein kinase II inhibitor, A-3, and H-7 inhibited translocation of p40-phox and activation of NADPH oxidase. Furthermore, purified protein kinase C but not casein kinase II directly phosphorylated p40-phox of p40-phox/p47-phox/p67-phox complex. Together these observations suggest that p40-phox is phosphorylated by protein kinase C during neutrophil activation, and phosphorylation of p40-phox may be important for the activation of NADPH oxidase.
Someya
A
A
Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan.
Nunoi
H
H
Hasebe
T
T
Nagaoka
I
I
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D047390:Casein Kinase II; D003600:Cytosol / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006168:Guinea Pigs; D006801:Humans; D008934:Mitogens / Q000494:pharmacology; D008969:Molecular Sequence Data; D019255:NADPH Oxidases / Q000378:metabolism*; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011817:Rabbits; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004791:Enzyme Inhibitors; D008934:Mitogens; D010750:Phosphoproteins; C085072:neutrophil cytosol factor 40K; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D019255:NADPH Oxidases; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate