Figure 4.

RNA is required for the nucleolar localization of ZPR1. HEp-2 cells were grown on microscopic slides, permeabilized with 0.1% Triton X-100 for 3 min on ice, washed, and digested (60 min at 37°C) with 0.1 mg/ml DNase I in PBS containing 5 mM MgCl₂ or with 0.1 mg/ml RNase A in PBS. The cells were washed in PBS and processed for indirect immunofluorescence. Buffers without enzymes served as negative controls. A human antibody to snRNP or a monoclonal antibody to DNA was used to monitor the efficiency of DNase I and RNase A digestions, respectively. The effect of DNase I (A) and RNase A (B) is presented.