The gRNA 3' oligo[U] tail is the major target for gRNA/p110 complex formation. A. The three indicated labeled synthetic RNAs were incubated with TS mitochondrial extract, and the presence of a gel-shifted band determined by native 4% acrylamide gel analysis. Lanes 1, 4, and 7 contain control samples with no extract. Lanes 2-3, 5-6, and 8-9 represent duplicate samples incubated with TS extract. The gRNA used is gND7-II. pGem RNA+oligo[U] is a short pGem transcript with 13 U's at the 3' end. The arrows indicate the p110-specific bands. B. gND7-II gRNA without an oligo[U] tail (-oligo[U]), with an oligo(C) tail (+oligo[C]), and with an oligo[U] tail (+oligo[U]) were incubated with TS mitochondrial extract (in duplicate), and the relative amount of the gel-shifted band (arrow) determined by native gel analysis. The percentage of label in the gel-shifted p110-specific bands using the modified gRNAs as compared to the amount of label in the band using the normal gRNA are shown below the lanes.