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. 2003 Mar;23(5):1798–1807. doi: 10.1128/MCB.23.5.1798-1807.2003

FIG. 3.

FIG. 3.

Nob1p is associated with pre-40S ribosomal particles. (A) The upper panel shows sedimentation of TAP-tagged Nob1p on a 10 to 50% sucrose gradient. The levels of the Nob1-TAP protein were determined by immunoblot analysis. The lower panel shows Northern analysis of the levels of the 20S pre-rRNA. Positions of 40S and 60S ribosomal subunits and 80S ribosomes are indicated, as determined by ethidium staining of the RNA recovered from each fraction (data not shown). (B and C) Northern analysis (B) and primer extension analyses (C) of rRNAs and pre-rRNAs coprecipitated with Nob1-TAP. RNA was extracted from whole cells (Tot.) and affinity-purified fractions from tagged (+ lane) and nontagged isogenic wild-type strain (− lane). The Northern blot membrane was consecutively hybridized with the probes indicated (see Fig. 6A for the locations of the probes used). The primer extension stop detected with oligonucleotide 004 is due to the cytoplasmic dimethylation of the 20S pre-rRNA at two consecutive A residues near the 3′ end of the 18S rRNA.