A Noc complex specifically involved in the formation and nuclear export of ribosomal 40 S subunits

J Biol Chem. 2003 Feb 7;278(6):4072-81. doi: 10.1074/jbc.M208898200. Epub 2002 Nov 20.

Abstract

Formation and nuclear export of 60 S pre-ribosomes requires many factors including the heterodimeric Noc1-Noc2 and Noc2-Noc3 complexes. Here, we report another Noc complex with a specific role in 40 S subunit biogenesis. This complex consists of Noc4p, which exhibits the conserved Noc domain and is homologous to Noc1p, and Nop14p, a nucleolar protein with a role in 40 S subunit formation. Moreover, noc4 thermosensitive mutants are defective in 40 S biogenesis, and rRNA processing is inhibited at early cleavage sites A(0), A(1), and A(2). Using a fluorescence-based visual assay for 40 S subunit export, we observe a strong nucleolar accumulation of the Rps2p-green fluorescent protein reporter in noc4 ts mutants, but 60 S subunit export was normal. Thus, Noc4p and Nop14p form a novel Noc complex with a specific role in nucleolar 40 S subunit formation and subsequent export to the cytoplasm.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cell Nucleus / metabolism*
  • Chromatography, Affinity
  • DNA Primers
  • Molecular Sequence Data
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Plasmids
  • Protein Transport
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Ribosomes / metabolism*
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins / chemistry
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Sequence Homology, Amino Acid

Substances

  • DNA Primers
  • Noc4 protein, S cerevisiae
  • Nuclear Proteins
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins