Fig. 4. Subcellular distribution of endogenous ADAR2. Schematic diagram comparing hADAR1 and hADAR2. The numbers indicated at the C-terminus represent size of the protein in amino acids. The most important domains of hADAR1 are indicated as follow: ZBDs, Z-DNA-binding domains (light gray); dsRBDs, double-stranded RNA binding domains (black boxes); deaminase domain (dark gray box). (A) HeLa cells were immunolabeled with anti-ADAR2 antibody. The labeling pattern is diffuse throughout the nucleoplasm, with concentration in nucleoli. The relative concentration of ADAR2 staining in the nucleolus varies from cell to cell. (B) A western-blot analysis of total (T) and nuclear (N) HeLa cell extracts. Cell extracts were prepared and fractionated by SDS-PAGE. Western blotting was then performed with anti-ADAR2 antibody (Ab 70). Extracts of HeLa cells transiently transfected with FlisADAR2 are shown in lane 3. Molecular weight markers are shown on the left. (C,D) Cryosections of neurosecretory neurons from the hypothalamic supraoptic nucleus were double-labeled with antibodies directed against fibrillarin (C) and ADAR2 (D). ADAR2 is predominantly detected in nucleoli, which can be readily identified by the fibrillarin staining. Bar, 10 µm.