Involvement of several protein kinases in the phosphorylation of p47-phox

Protein kinases are stimulated during the microbicidal responses of neutrophils. In particular, the activation of protein kinase C causes the phosphorylation of p47-phox, one of the cytosolic components of NADPH oxidase. Phosphorylated p47-phox was accumulated not only by PMA treatment, but also by calyculin A treatment. However, p47-phox phosphorylated by calyculin A treatment lost its ability to activate NADPH oxidase. Several protein kinases were activated by calyculin A treatment. Furthermore the phosphorylation sites of p47-phox by calyculin A treatment were different from those by PMA treatment. These results indicated that calyculin A-activated kinases phosphorylated p47-phox at the site different from that phosphorylate by protein kinase C, resulting in suppression of NADPH oxidase activation.