Repression of KREPB4 expression in RNAi cells affects RNA editing catalytic activities in vitro. Glycerol gradient fractions (fraction 1, top) from whole cell lysates of KREPB4 RNAi cells grown in the absence (expressed) or in the presence (repressed) of tet were assayed for in vitro precleaved insertion (A) or precleaved deletion (B) editing activities. The radiolabeled input RNAs (Inp), to which two Us are added (+2U), or from which four Us are removed (−4U), ligated products of unprocessed 5′ and 3′ input RNAs (Lig), and edited (Ed) products are indicated. Positive control reactions (+) were performed using a fraction of ∼20S editosome that contains peak editing activity, which was omitted from negative control reactions (−p).
