RESOLUTION OF MAJOR PROTEIN-KINASE SUBSTRATES IN NEUTROPHIL CYTOSOL IN RESPONSE TO DAG PS AND ARACHIDONIC-ACID STIMULATION AND THE SELECTIVE ACTION OF VARIOUS PROTEIN-KINASE INHIBITORS/

Stimulation of human neutrophils induces phosphorylation of several ce llular proteins. Human neutrophils posses calcium-dependent protein ki nase C (PKC) alpha and beta isoforms and calcium-independent n isoform s. Little is known, however, of the physiological substrates of each i soform. In this study, we characterized the substrates of calcium-depe ndent and -independent PKC isoforms and the substrate of PKC activated by arachidonic acid. Furthermore, we found that the PKC inhibitor H-7 failed to inhibit phosphorylation of endogenous substrates of calcium -independent PKC activity. These may help to understand the role of PK C in neutrophil activation and shed light on the different responses e licited by H-7 in intact cells.