Differential mechanisms of translocation of protein kinase C to plasma membranes in activated human neutrophils

S. Pontremoli, E. Melloni, M. Michetti, F. Salamino, B. Sparatore, O. Sacco, B. L. Horecker

Research output: Contribution to journalArticlepeer-review


Three classes of activators of human neutrophils that induce the intracellular translocation of protein kinase C from the cytosol to the particulate fraction were compared for their effects on the properties of the particulate (membrane-bound) enzyme. In cells stimulated with 10 ng/ml of phorbol-12-myristate-13-acetate (PMA) the particulate enzyme is almost fully active in the absence of added Ca2+ or phospholipids and this activity is not released by the Ca2+-chelator EDTA. In contrast, binding of protein kinase C to the particulate fraction in cells treated with the chemotactic factor f-Met-Leu-Phe (fMLF) or with the ionophore A-23187 plus Ca2+ is observed only when the cells are lysed in the presence of 1 mM Ca2+. With these stimuli the particulate enzyme retains a nearly absolute requirement for Ca2+ and phospholipids. Thus only the full intercalation of protein kinase C caused by PMA, which is resistant to removal by chelators stabilizes an active form of protein kinase C in the neutrophil membrane. In confirmation of this conclusion, in isolated plasma membranes loaded with partially purified protein kinase C by incubation with 5 μM Ca2+ further incubation with PMA, but not with fMLF, caused a significant fraction of the bound PKC to become resistant to removal by chelators, and to be nearly fully active in the absence of added activators.

Original languageEnglish
Pages (from-to)228-234
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number1
Publication statusPublished - Apr 14 1986

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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