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 neuroblastoma cells. Confocal microscopy revealed that PKC alpha is present in the nucleoplasm and that this localization does not change after stimulation with phorbol ester, However, as revealed by extraction experiments, phorbol ester leads to a firmer association of PKC alpha with nuclear components. Our findings suggest that PKC alpha not only associates with lipids but also with proteins inside the nucleus, The presence of active PKC alpha inside the nucleus allows the enzyme to phosphorylate not only proteins at the nuclear envelope but also proteins in the nucleoplasm. (C) 1997 Federation of European Biochemical Societies.