Figure 2.

T-UTPs localize to nucleoli in HeLa cells. (A) HeLa cells were stained with rhodamine-conjugated affinity-purified antibodies against UTP10 (upper panels) and UTP4 (lower panels). Nuclei were visualized with DAPI, and nucleoli were identified by co-staining with FITC-conjugated affinity-purified antibodies against UBF. (B) Nucleoli purified from HeLa cells were stained with UTP10 or UTP4 antibodies as above. FC/DFC structures within nucleoli were identified by co-staining with FITC-conjugated antibodies against either the pol I subunit RPA43 or UBF. Nucleoli were revealed using DIC optics. (C) HeLa cells were transfected with plasmids encoding V5 epitope-tagged UTP4, UTP5, and UTP17. Tagged proteins were identified with a monoclonal antibody against the V5 tag combined with a rhodamine-labeled secondary antibody. Nucleoli were visualized with UBF antibodies as above. Nontransfected cells provided a control. Scale bars, 10 μm.