Figure 5.

A subset of box C/D snoRNAs accumulate on pre-ribosomes when Dbp3 is lacking. Extracts were separated by sucrose density gradient centrifugation as in (Figure 4G). Fractions containing either (pre-)ribosomal complexes or non-ribosome-associated snoRNPs were pooled and RNA was extracted. Polyadenylation and reverse transcription were performed and the levels of each of the 75 yeast snoRNAs in each sample was determined by RT-qPCR. The relative distribution of each box C/D snoRNA between (pre-)ribosome-bound and non-ribosome-associated fractions was calculated and differences in this ratio between the wild type and Δdbp3 strains are shown graphically. Three independent experiments were performed and the data are presented as mean ± standard deviation. Dashed red lines indicate the upper and low thresholds for significant accumulation and exclusion of snoRNAs on/from pre-ribosomes respectively.