IS DNA TOPOISOMERASE II-BETA A NUCLEOLAR PROTEIN

We have carried out immunofluorescence labelling of two human cell typ es, Hela cells and peripheral blood lymphocytes, prepared by several d ifferent fixation/permeabilization protocols using a variety of antibo dies against DNA Topoisomerase II (Topo II). We have found that the di stribution of Topo II alpha was overall similar during interphase and mitosis to that previously reported, regardless of antibody and of sam ple preparation. On the other hand, the interphase distribution of Top o II beta was quite variable, depending both on the antibody and on th e method used to prepare the sample. Our interpretation of the data is that, like Topo II alpha, Topo II beta is primarily a nucleoplasmic p rotein, but that unlike Topo II alpha, small amounts are also associat ed with intranucleolar chromatin. (C) 1996, Wiley-Liss, Inc.