EXOSC9 Human

EXOSC9 is a non-catalytic component of the RNA exosome complex which has 3'->5' exoribonuclease activity and take part in many cellular RNA processing and degradation events. In the nucleus, the RNA exosome complex take part in proper maturation of stable RNA species like rRNA, snRNA and snoRNA, in the elimination of RNA processing by-products and non-coding 'pervasive' transcripts like anti-sense RNA species and promoter-upstream transcripts (PROMPTs), and of mRNAs with processing defects, thereby limiting or excluding their export to the cytoplasm. The RNA exosome is involved in Ig class switch recombination (CSR) and/or Ig variable region somatic hypermutation (SHM) by targeting AICDA deamination activity to transcribed dsDNA substrates. In the cytoplasm, the RNA exosome complex takes part in general mRNA turnover and specifically degrades inherently unstable mRNAs containing AU-rich elements (AREs) within their 3' untranslated regions, and in RNA surveillance pathways, inhibiting translation of aberrant mRNAs. EXOSC9 takes part in degradation of histone mRNA. The catalytic inactive RNA exosome core complex of 9 subunits (Exo-9) is proposed to be an essential part in the binding and presentation of RNA for ribonucleolysis, and acts as a scaffold for the association with catalytic subunits and accessory proteins or complexes. EXOSC9 binds to ARE-containing RNAs.