Figure 4

Terminal processing of C/D box snoRNAs. (A) Profiles of sequencing reads obtained from two small RNA seq libraries for three selected C/D box snoRNAs (SNORD8, SNORD21 and SNORD29). Upper: sdRNA sequencing, 18 to 30 nucleotides. Lower: sRNA sequencing, 20 to 200 nucleotides. Secondary structure annotation of the terminal closing stem is given on the top of the figure, while the locations of C and D motifs are shown on the bottom. (B) Detailed analysis of terminal stem processing for C/D box snoRNA expressed in HEK293 cells. The y-axis indicates individual nucleotides, with their specific identity for the nucleotides in C/D boxes and position relative to the boxes for the flanking nucleotides. Each column corresponds to a snoRNA, whose identity is shown at the top of the panel. Grey boxes indicate nucleotides that are predicted to be paired in the terminal stem. The size of black boxes is proportional to the number of sRNA sequencing reads that start (5' end) or end (3' end) at a particular nucleotide. See Additional File 16 for analysis of all C/D box snoRNAs expressed in HEK293 cells. sdRNA: small derived RNA; snoRNA: small nucleolar RNA; sRNA: small RNA