Non-catalytic component of the RNA exosome complex which has3'->5' exoribonuclease activity and participates in a multitude ofcellular RNA processing and degradation events. In the nucleus, the RNAexosome complex is involved in proper maturation of stable RNA speciessuch as rRNA, snRNA and snoRNA, in the elimination of RNA processingby-products and non-coding 'pervasive' transcripts, such as antisenseRNA species and promoter-upstream transcripts (PROMPTs), and of mRNAswith processing defects, thereby limiting or excluding their export tothe cytoplasm. The RNA exosome may be involved in Ig class switchrecombination (CSR) and/or Ig variable region somatic hypermutation (SHM) by targeting AICDA deamination activity to transcribed dsDNAsubstrates. In the cytoplasm, the RNA exosome complex is involved ingeneral mRNA turnover and specifically degrades inherently unstablemRNAs containing AU-rich elements (AREs) within their 3' untranslatedregions, and in RNA surveillance pathways, preventing translation ofaberrant mRNAs. It seems to be involved in degradation of histone mRNA. The catalytic inactive RNA exosome core complex of 9 subunits (Exo-9) is proposed to play a pivotal role in the binding and presentation ofRNA for ribonucleolysis, and to serve as a scaffold for the associationwith catalytic subunits and accessory proteins or complexes. EXOSC2 asperipheral part of the Exo-9 complex stabilizes the hexameric ring ofRNase PH-domain subunits through contacts with EXOSC4 and EXOSC7.

MAMEMRLPVARKPLSERLGRDTKKHLVVPGDTITTDTGFMRGHGTYMGEEKLIASVAGSVERVNKLICVKALKTRYIGEVGDIVVGRITEVQQKRWKVETNSRLDSVLLLSSMNLPGGELRRRSAEDELAMRGFLQEGDLISAEVQAVFSDGAVSLHTRSLKYGKLGQGVLVQVSPSLVKRQKTHFHDLPCGASVILGNNGFIWIYPTPEHKEEEAGGFIANLEPVSLADREVISRLRNCIISLVTQRMMLYDTSILYCYEASLPHQIKDILKPEIMEEIVMETRQRLLEQEG