Fig. 6. Proteasome-dependent degradation of DQ-OVA occurs in distinct subnuclear domains. Panels (A-H) show a confocal fluorescence micrograph of a representative HEp-2 cell microinjected with DQ-OVA (green), and a corresponding overview of untreated and microinjected cells (arrowheads) on the left. HEp-2 cells were double labelled (red) with ß-tubulin (A), lamin A/C (B), fibrillarin (C), SC35 (D), PML (E), RNA polymerase II (pol II, F), ubiquitin (G), and proteasomes (H). Microinjected DQ-OVA co-localizes partially with SC35, PML, pol II, ubiquitin and proteasomes in nucleoplasmic foci (yellow). (I) Quantification of co-localization between DQ-OVA and ß-tubulin or nuclear proteins in microinjected cells. Co-localization of DQ-OVA with ß-tubulin was quantified by defining whole cells as regions of interest (asterisk). Co-localization with nuclear proteins and nucleoplasmic proteasomes (two asterisks) was determined using cell nuclei as regions of interest. Note, exclusion of DQ-OVA from the nucleus in cells that were exclusively microinjected into the cytoplasm (open arrowheads). Scale bars, 5 µm.