Nob1p is required for cleavage of the 3' end of 18S rRNA

Mol Cell Biol. 2003 Mar;23(5):1798-807. doi: 10.1128/MCB.23.5.1798-1807.2003.


We report the characterization of a novel factor, Nob1p (Yor056c), which is essential for the synthesis of 40S ribosome subunits. Genetic depletion of Nob1p strongly inhibits the processing of the 20S pre-rRNA to the mature 18S rRNA, leading to the accumulation of high levels of the 20S pre-rRNA together with novel degradation intermediates. 20S processing occurs within a pre-40S particle after its export from the nucleus to the cytoplasm. Consistent with a direct role in this cleavage, Nob1p was shown to be associated with the pre-40S particle and to be present in both the nucleus and the cytoplasm. This suggests that Nob1p accompanies the pre-40S ribosomes during nuclear export. Pre-40S export is not, however, inhibited by depletion of Nob1p.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Alleles
  • Amino Acid Motifs
  • Amino Acid Sequence
  • Blotting, Northern
  • Carrier Proteins / metabolism*
  • Cell Nucleus / metabolism
  • Centrifugation, Density Gradient
  • Cytoplasm / metabolism
  • Fluorescent Antibody Technique, Indirect
  • Fungal Proteins / metabolism
  • Microscopy, Fluorescence
  • Models, Genetic
  • Molecular Sequence Data
  • Nuclear Proteins
  • Oligonucleotides / pharmacology
  • Protein Structure, Tertiary
  • RNA, Ribosomal / metabolism
  • RNA, Ribosomal, 18S / metabolism*
  • Ribosomes / metabolism
  • Saccharomyces cerevisiae Proteins*
  • Sequence Homology, Amino Acid
  • Sucrose / pharmacology
  • Time Factors
  • Two-Hybrid System Techniques


  • Carrier Proteins
  • Fungal Proteins
  • NOB1 protein, S cerevisiae
  • Nuclear Proteins
  • Oligonucleotides
  • RNA, Ribosomal
  • RNA, Ribosomal, 18S
  • Saccharomyces cerevisiae Proteins
  • Sucrose