Exosome complex component RRP45 (EXOSC9)

Non-catalytic component of the RNA exosome complex which has 3'->5' exoribonuclease activity and participates in a multitude of cellular RNA processing and degradation events. In the nucleus, the RNA exosome complex is involved in proper maturation of stable RNA species such as rRNA, snRNA and snoRNA, in the elimination of RNA processing by-products and non-coding'pervasive' transcripts, such as antisense 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 could be involved in Ig class switch recombination (CSR) or Ig variable region somatic hypermutation (SHM) by targeting AICDA deamination activity to transcribed dsDNA substrates. In the cytoplasm, the RNA exosome complex is involved in overall mRNA turnover and specifically degrades inherently unstable mRNAs containing AU-rich elements (AREs) in their 3' untranslated regions, and in RNA surveillance pathways, preventing translation of aberrant mRNAs.