INFLUENCE OF CALCIUM ON THE SUBCELLULAR-DISTRIBUTION OF PROTEIN KINASE-C IN HUMAN-NEUTROPHILS - EXTRACTION CONDITIONS DETERMINE PARTITIONING OF HISTONE-PHOSPHORYLATING ACTIVITY AND IMMUNOREACTIVITY BETWEEN CYTOSOL AND PARTICULATE FRACTIONS

Abstract

Activation of the neutrophil respiratory burst is thought to involve a translocation and activation of protein kinase C. We report that the presence of Ca2+ during the disruption of unstimulated human neutrophils and cytoplasts resulted in an increase in protein kinase C activity (histone phosphorylation) and immunoreactive protein kinase C species in the particulate (membrane) fraction and a reduction in such activities in the cytosol. This Ca2+-induced translocation of activity was concentration-dependent and occurred at physiologically relevant concentrations of Ca2+ (30-500 nM). The Ca2+-induced membrane association of protein kinase C could be reversed by removal of Ca2+. These findings..