Association of Noc2 with early LSU precursors after <i>in vivo</i> depletion of LSU r-proteins required for early LSU pre-rRNA processing.

<p>The indicated yeast strains, expressing a chromosomally-encoded TAP-tagged version of the LSU biogenesis factor Noc2, together with either the indicated or no LSU r-protein gene under control of the galactose-inducible GAL1/10 promoter, were cultivated for four hours in glucose-containing medium to shut down expression of the respective LSU r-protein gene. Noc2-TAP and associated pre-ribosomal particles were then affinity purified from the corresponding cellular extracts as described in Materials and Methods. The (pre-) rRNA content of total cellular extracts (“Input” lanes 1–12) or of parts of the affinity purified fractions (“IP”lanes 13–24) was analyzed by northern blotting. (pre-) rRNAs detected by DNA oligonucleotide probes shown on the right are denoted on the left. Equal signal intensities in the Input and IP fractions indicate that 4% of the respective (pre-)rRNA population co-purified with Noc2-TAP.