LOCALIZATION OF NONCONVENTIONAL PROTEIN-KINASE-C ISOFORMS IN BOVINE BRAIN-CELL NUCLEI

Using Western blotting and immunofluorescence microscopy we detected t he protein kinase C isoforms delta, epsilon and zeta in isolated cell nuclei from bovine cerebral cortex. Both protein kinase (PKC) delta an d PKC epsilon are present in higher concentrations in neuronal than in glial nuclei and are located inside the nucleus and at the nuclear en velope. There they give a punctate staining in immunofluorescence micr oscopy. PKC zeta is also present both in the nucleoplasm and at the nu clear envelope. PKC eta could not be detected in the cell nuclei and, even in the homogenate of cerebral cortex, this isoform is present onl y in very low concentrations. The antibody against PKC eta bound stron gly to a nucleoplasmic protein with an apparent molecular mass of 99 k Da. The localization of non-conventional PKC isoforms at the cell nucl eus strongly indicates that these isoforms are directly involved in th e regulation of nuclear processes.