Translocation of protein kinase C isoforms in rat neutrophils

In this study, we examined the protein kinase C (PKC) isoforms present in cytosol and membrane fractions of rat neutrophils by Western blotting analysis with monoclonal antibodies against PKC isoforms and demonstrated that rat neutrophils express at least three conventional PKCs (cPKC), alpha, beta and gamma, four novel PKCs (nPKC), delta, epsilon, theta and mu, and three atypical PKCs (aPKC), iota, lambda and zeta, although PKC lambda and zeta were barely detected. Cells stimulated with phorbol 12-myristate 13-acetate (PMA) induce a sustained and marked translocation of cPKC and nPKC from the cytosol to particulate fraction. A concentration-dependence of PMA on the membrane translocation of PKC isoforms was observed. Treatment with formyl-Met-Leu-Phe (fMLP), in contrast with PMA, caused a transient and less prominent association of cPKC and nPKC with particulate fraction. However, the distribution of PKC iota isoform was affected neither by fMLP nor by PMA. These data indicate that the rat neutrophils contain PKCs of three isoform families and the membrane translocation of cPKC and nPKC was observed in cells in response to PMA as well as to fMLP.