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Phosphorylation of p40‐phox during activation of neutrophil NADPH oxidase
Author(s) -
Someya Akimasa,
Nunoi Hiroyuki,
Hasebe Takeshi,
Nagaoka Isao
Publication year - 1999
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.66.5.851
Subject(s) - nadph oxidase , phosphorylation , superoxide , cytosol , protein kinase c , kinase , biology , phorbol , microbiology and biotechnology , biochemistry , protein kinase a , enzyme
NADPH oxidase, a superoxide‐producing enzyme in phagocytic cells, consists of membrane‐associated cytochrome b5 58 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 32 P‐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. J. Leukoc. Biol. 66: 851–857; 1999.