Cic1p/Nsa3p is required for synthesis and nuclear export of 60S ribosomal subunits

RNA. 2003 Dec;9(12):1431-6. doi: 10.1261/rna.5130503.


Cic1p/Nsa3p was previously reported to be associated with the 26S proteasome and required for the degradation of specific substrates, but was also shown to be associated with early pre-60S particles and to be localized to the nucleolus. Here we report that Cic1p/Nsa3p is required for the synthesis of 60S ribosome subunits. A temperature-sensitive lethal cic1-2 point mutation inhibits synthesis of the mature 5.8S and 25S rRNAs. Release of the pre-60S particles from the nucleolus to the nucleoplasm was also inhibited as judged by the nuclear accumulation of an Rpl11b-GFP reporter construct. We suggest that Cic1p/Nsa3p associates early with nascent preribosomal particles and is required for correct processing and nuclear release of large ribosomal subunit precursors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Biological Transport
  • Carrier Proteins / physiology*
  • Cell Nucleus / metabolism*
  • DNA Primers
  • Green Fluorescent Proteins
  • Luminescent Proteins / metabolism
  • RNA, Ribosomal / metabolism*
  • Recombinant Fusion Proteins / metabolism
  • Ribosomes*
  • Saccharomyces cerevisiae Proteins / physiology*


  • Carrier Proteins
  • Cic1 protein, S cerevisiae
  • DNA Primers
  • Luminescent Proteins
  • RNA, Ribosomal
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • Green Fluorescent Proteins