FIGURE 4.

NPM1 serine-48 is crucial for binding to PCV4 Cap. (A,B) The NPM1-OligoD (1–117 aa) interacted with PCV4 Cap. HEK293T cells were co-transfected with expression plasmids GFP-NPM1-WT or its serial GFP-NPM1 truncated mutants M1 to M6, together with the Flag-PCV4-Cap or Flag-gst-PCV4-Cap plasmid. The cell lysate extracts were immunoprecipitated or subjected to a GST pull-down assay followed by western blotting using the indicated antibodies. (C,D) Mapping the critical amino acids of OligoD required for interaction with PCV4 Cap. HEK293T cells were co-transfected with NPM1 or NPM1 mutant plasmids (NPM1-S48A, NPM1-S48E, NPM1-S88A, NPM1-S88E, NPM1-T95A, or NPM1-T95D), together with the Flag-PCV4-Cap or Flag-gst-PCV4-Cap plasmid, and the cell lysate extracts were immunoprecipitated or subjected to a GST pull-down assay followed by western blotting using the indicated antibodies.