Presence of a beta II protein kinase C-selective nuclear membrane activation factor in human leukemia cells.

摘要: In human promyelocytic (HL60) leukemia cells beta II protein kinase C (PKC) is selectively translocated to the nucleus in response proliferative stimuli. At nucleus, PKC directly phosphorylates nuclear envelope polypeptide lamin B at two consensus phosphorylation sites, Ser395 and Ser405. Phosphorylation of these sites by leads solubilization indicative mitotic breakdown vitro (Hocevar, B.A., Burns, D.J., Fields, A.P. (1993) J. Biol. Chem. 268, 7545-7552). We have now investigated molecular basis for PKC-selective translocation using an reconstitution system. find that 10-20 times rate alpha PKC, whereas both kinases phosphorylate soluble similar rates. Comparative tryptic phosphopeptide analysis demonstrates identical Ser405, on B. These data suggest a component(s) confers activation phosphorylation. Extraction envelopes with either non-ionic detergent (2% n-octyl glucoside) or organic solvent (CHCl3/CH3OH/H2O; 10:10:3) abolishes Nuclear membrane extracts reconstitute phosphorylation, indicating presence factor (NMAF). NMAF activates histone H1 activity 3-4-fold above level achieved optimal concentrations Ca2+, diacylglycerol, phosphatidylserine. Finally, not affected exhaustive protease treatment, suggesting it lipid(s) lipid metabolite. plays physiologic role PKC.