Fig 3. Mutants of DBP5 show no unique defects in the biogenesis of ribosomal subunits.
(A) The steady state levels of the different rRNAs and their precursors in the dbp5 mutants rat8-2 and rat8-7 are comparable with those in the export mutants rat7-1 and xpo1-1. Northern blot analyses with DIG-labeled RNA probes targeting the indicated rRNA species and U2 snRNAs (loading control) are shown. Total RNA of the different strains was extracted upon 1 h shifts to their restrictive temperatures and 1 μg was separated by formaldehyde/MOPS-agarose gel electrophoresis. (B) The total amount of 40S and 60S subunits is not altered in dbp5 mutants. Flow through photometry (A254nm = absorbance at 254 nm) profiles of ultra-centrifuged sucrose gradients from rat8-2 and rat8-7 cells shifted to their indicated non-permissive temperatures and treated with 100 mM EDTA reveal no significant change of their peak sizes and the 60S to 40S subunit ratio in comparison to the wild type. In contrast, rpl10(G161D) served as a positive control of the assay and shows a decreased 60S peak.