Is DNA topoisomerase II beta a nucleolar protein?
We have carried out immunofluorescence labelling of two human cell types, HeLa cells and peripheral blood lymphocytes, prepared by several different fixation/permeabilization protocols using a variety of antibodies against DNA Topoisomerase II (Topo II). We have found that the distribution of Topo II alpha was overall similar doing interphase and mitosis to that previously reported, regardless of antibody and of sample preparation. On the other land, the interphase distribution of Topo II beta was quite variable, depending both on the antibody and on the method used to prepare the sample. Our interpretation of the data is that, like Topo II alpha, Topo II beta is primarily a nucleoplasmic protein, but that unlike Topo II alpha, small amounts are also associated with intranucleolar chromatin.
Chaly
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Department of Biology, Carleton University, Ottawa ON, Canada.
Brown
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DL
D000818:Animals; D002463:Cell Membrane Permeability; D002466:Cell Nucleolus / Q000201:enzymology*; D004250:DNA Topoisomerases, Type II / Q000032:analysis*; D004268:DNA-Binding Proteins; D019084:Fluorescent Antibody Technique, Indirect; D006367:HeLa Cells; D006801:Humans; D008214:Lymphocytes / Q000201:enzymology; D051379:Mice; D009697:Nucleolus Organizer Region / Q000201:enzymology*; D000075223:Poly-ADP-Ribose Binding Proteins
D004268:DNA-Binding Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; D004250:DNA Topoisomerases, Type II; C000618814:TOP2B protein, human