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The exosome: a conserved eukaryotic RNA processing complex containing multiple 3'-->5' exoribonucleases.

We identified a complex in S. cerevisiae, the "exosome," consisting of the five essential proteins Rrp4p, Rrp41p, Rrp42p, Rrp43p, and Rrp44p (Dis3p). Remarkably, four of these proteins are homologous to characterized bacterial 3'-->5' exoribonucleases; Rrp44p is homologous to RNase II, while Rrp41p, Rrp42p, and Rrp43p are related to RNase PH. Recombinant Rrp4p, Rrp44p, and Rrp41p are 3'-->5' exoribonucleases in vitro that have distributive, processive, and phosphorolytic activities, respectively. All components of the exosome are required for 3' processing of the 5.8S rRNA. Human Rrp4p is found in a comparably sized complex, and expression of the hRRP4 gene in yeast complements the rrp4-1 mutation. We conclude that the exosome constitutes a highly conserved eukaryotic RNA processing complex.

Pubmed ID: 9390555


  • Mitchell P
  • Petfalski E
  • Shevchenko A
  • Mann M
  • Tollervey D



Publication Data

November 14, 1997

Associated Grants


Mesh Terms

  • Amino Acid Sequence
  • Exoribonucleases
  • Fungal Proteins
  • Genetic Complementation Test
  • HeLa Cells
  • Humans
  • Molecular Sequence Data
  • Molecular Weight
  • Multienzyme Complexes
  • Mutation
  • RNA Processing, Post-Transcriptional
  • RNA, Ribosomal, 5.8S
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins