Studies on the nature and activation of O2- -forming NADPH oxidase of leukocytes. II. Relationships between phosphorylation of a component of the enzyme and oxidase activity

The activation of O2- -formation by neutrophil NADPH oxidase is associated with phosphorylation of several membrane and cytosolic proteins. In the membranes a phosphoprotein of 32 kDa belonging to the NADPH oxidase-cytochrome b-245 system (P. Bellavite et al., Free Rad. Res. Commun., 1, 11 (1985] showed the highest relative increase of 32Pi incorporation. Concomitant with the phosphorylation, a shift of the apparent molecular mass of the protein from 31 to 32 kDa occurred. The time-course, the sensitivity to trifluoperazine and the dose-dependence of phosphorylation were similar to those of O2- forming activity, except that the latter showed a longer lag-time than the former. The increase of the 32 kDa phosphoprotein was also comparable to the kinetics of cytochrome b-245 reduction by anaerobically activated neutrophils. The phosphorylation and the NADPH oxidase were triggered by various stimulants including phorbol myristate acetate, opsonized zymosan, arachidonic acid and sodium fluoride. With arachidon