Fig. 2. dsRNA binding activity of NRF. Uniformly ³²P-labeled 469 nt IFN- T7-derived RNA (see Methods section) was incubated with in vitro produced full-length NRF fusion protein or the indicated deletion mutants. The reaction mixture was subjected to electrophoresis on a native gel to separate RNA-protein complexes from the free probe. The arrows indicate the migration of IFN- RNA as a free probe and as complexes with NRF and PKR. The autoradiogram shows free and bound RNA. Addition of antibody directed against the Myc-tag (that specifically inhibits the complex formation between His-Myc-NRF and IFN-) is indicated.