In the eukaryotic ribosomal RNA processing pathway, a complex of ten riboexonucleases called the exosome that plays a central role in the precise formation of the 3' ends of several types of RNAs.

The exosome also destroys excess ribosomal RNA precursors and unused intermediates and degrades poly(A)-mRNAs in the cytoplasm.

In the nucleus, the complex appears to function in a regulated mRNA surveillance system that degrades transcripts in response to defects in the mRNA processing and export pathways.

References

 Butler JS. The yin and yang of the exosome. Trends Cell Biol. 2002 Feb;12(2):90-6. PMID: #11849973#