FIG. 3.

Stems I and II of the box C/D motif are essential for 15.5K binding. (A) Sequence and structure of U14 snoRNA stem I and stem II mutations. The conserved nucleotides of the box C/D motif are represented as in Fig. 1A. (B) Gel mobility shift analysis of the interaction of recombinant 15.5K with the stem I and stem II mutants. The wild-type (wt) U14 as well as the mutant transcripts outlined in panel A were incubated with recombinant 15.5K, and the resulting RNA-protein complexes were resolved on a 6% native polyacrylamide gel. The presence (+) or absence (−) of 15.5K is indicated above each lane. The position of the protein-RNA complex (RNP) and the free RNA is indicated on the right. The RNA used is indicated above each lane.