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Proteomic analysis of human Nop56p-associated pre-ribosomal ribonucleoprotein complexes. Possible link between Nop56p and the nucleolar protein treacle responsible for Treacher Collins syndrome.

Nop56p is a component of the box C/D small nucleolar ribonucleoprotein complexes that direct 2'-O-methylation of pre-rRNA during its maturation. Genetic analyses in yeast have shown that Nop56p plays important roles in the early steps of pre-rRNA processing. However, its precise function remains elusive, especially in higher eukaryotes. Here we describe the proteomic characterization of human Nop56p (hNop56p)-associated pre-ribosomal ribonucleoprotein complexes. Mass spectrometric analysis of purified pre-ribosomal ribonucleoprotein complexes identified 61 ribosomal proteins, 16 trans-acting factors probably involved in ribosome biogenesis, and 29 proteins whose function in ribosome biogenesis is unknown. Identification of pre-rRNA species within hNop56p-associated pre-ribosomal ribonucleoprotein complexes, coupled with the known functions of yeast orthologs of the probable trans-acting factors identified in human, demonstrated that hNop56p functions in the early to middle stages of 60 S subunit synthesis in human cells. Interestingly, the nucleolar phosphoprotein treacle, which is responsible for the craniofacial disorder associated with Treacher Collins syndrome, was found to be a constituent of hNop56p-associated pre-rRNP complexes. The association of hNop56p and treacle within the complexes was independent of rRNA integrity, indicating a direct interaction. In addition, the protein compositions of the treacle-associated and hNop56p-associated pre-ribosomal ribonucleoprotein complexes were very similar, suggesting functional similarities between these two complexes with respect to ribosome biogenesis in human cells.

Pubmed ID: 12777385


  • Hayano T
  • Yanagida M
  • Yamauchi Y
  • Shinkawa T
  • Isobe T
  • Takahashi N


The Journal of biological chemistry

Publication Data

September 5, 2003

Associated Grants


Mesh Terms

  • Amino Acid Motifs
  • Blotting, Northern
  • Cell Line
  • Cell Nucleolus
  • Cell Nucleus
  • Electrophoresis, Polyacrylamide Gel
  • Epitopes
  • Humans
  • Immunohistochemistry
  • Mandibulofacial Dysostosis
  • Mass Spectrometry
  • Models, Genetic
  • Nuclear Proteins
  • Phosphoproteins
  • Precipitin Tests
  • Protein Binding
  • Protein Structure, Tertiary
  • Proteome
  • RNA, Ribosomal
  • Ribonucleases
  • Ribonucleoproteins
  • Ribosomes
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  • Transfection