FIG. 4.
UV cross-linking assay for binding EBER to PKR in Intestine 407. Neor- and EBER-expressing Intestine 407 cell clones (5 × 106) were transfected with a FLAG-tagged PKR-expressing plasmid by Lipofectamine. As a control, an EBER-expressing cell clone was transfected with a FLAG-tagged mutant PKR plasmid, which lacks the dsRNA-binding domain (indicated as EBER*). At 48 h posttransfection, cells were treated with or without UV irradiation, and the bound complexes were immunoprecipitated with anti-FLAG antibody. The RNA fraction was extracted from the immunoprecipitants, and then EBER1 and EBER2 RNAs were amplified by reverse transcription-PCR.