NUCLEAR-LOCALIZATION OF PROTEIN-KINASE C-ALPHA AND ITS ASSOCIATION WITH NUCLEAR-COMPONENTS IN NEURO-2A NEUROBLASTOMA-CELLS

Using activity measurements and Western blotting, we demonstrated that PKC alpha is constitutively present in nuclei of Neuro-2a neuroblasto ma cells. Confocal microscopy revealed that PKC alpha is present in th e nucleoplasm and that this localization does not change after stimula tion with phorbol ester, However, as revealed by extraction experiment s, phorbol ester leads to a firmer association of PKC alpha with nucle ar components. Our findings suggest that PKC alpha not only associates with lipids but also with proteins inside the nucleus, The presence o f active PKC alpha inside the nucleus allows the enzyme to phosphoryla te not only proteins at the nuclear envelope but also proteins in the nucleoplasm. (C) 1997 Federation of European Biochemical Societies.