FIG. 4.

Overexpression of different isoforms of PML as well as a PML mutant alters the biochemical composition of PML NBs. (A) Schematic diagram displaying the variable C-terminal domain of the various PML isoforms as well as the location of the three sumoylation mutation sites of the 3K-PMLIV protein (circled S). (B) Immunofluorescence microscopy of cells transfected with either no plasmid, PMLIV, PMLVI, or 3K-PMLIV. Lanes 1, 3, and 5, cells were labeled using an anti-PML antibody. Lanes 2, 4, and 6, cells were labeled with anti-Sp100, CBP, and Daxx antibodies, respectively. Exposure times were chosen so that the fluorescence signal did not saturate the detector. No contrast enhancement was performed in any of these images, so that the relationship of signal within the PML NBs relative to the nucleoplasmic background could be assessed qualitatively. Bar = 5 μm.