ANALYSIS OF NUCLEAR-LOCALIZATION OF LAMININ-BINDING PROTEIN-PRECURSORP40 (LBP P40)/

We isolated a monoclonal antibody M108, which recognized 40 kDa protei n (40) in the cytoplasm, the perinuclear region in interphase and the perichromosomal region during mitosis. As reported previously, it was revealed from the immunofluorescent observation and the biochemical an alyses that the nuclear p40 was associated both with the nuclear envel ope and the chromatin DNA in interphase nuclei. In this report, we iso lated the p40 from cytoplasmic particles, and identified it by extensi ve microsequencing as LBP/p40, which was considered to be a precursor of laminin binding protein p67 (LBP/p67). Epitope-tagged LBP/p40 was e xpressed in cultured cells, and the protein was localized in the nucle us as well as in the cytoplasm. Further analysis showed that the nucle ar LBP/p40 was tightly associated with the nuclear structures. (C) 199 6 Academic Press.