COACTIVATION OF PROTEIN-KINASE-C AND NADPH OXIDASE IN THE PLASMA-MEMBRANE OF NEUTROPHIL CYTOPLASTS

Enucleated, granule-free neutrophil cytoplasts, which in hypotonic media fully release cytosolic components and generate ghosts, have been used to study the cell localization of protein kinase C (PK-C). Treatment of cytoplasts with phorbol myristate acetate, a potent activator of neutrophil functions, triggers translocation of PK-C from the cytosol to the plasma membrane, with an activity recovery of 83 .+-. 16%. In the ghost fraction, PK-C catalyzes the phosphorylation of polypeptides with an apparent mol. wt. of 115K, 89K, 79K, 62K, 47K and 19K. From the plasma membrane PK-C can be extracted in an active form by Triton X-100 but not by EGTA. Translocation of PK-C is already evident at 5 sec and plateaus at about 50 sec. Activation of plasmalemmal, O2- generating NADPH oxidase by the phorbol ester is delayed by about 20 sec with respect to the activation of PK-C. Dose-response experiments show that the pattern of activation of O2- generation by cytoplasts strictly superimposes with the pattern of PK-C translocation.