EXOSC9 component of the exosome 3->5 exoribonuclease complex, a complex that degrades inherently unstable mRNAs containing AU-rich elements (AREs) within their 3-untranslated regions. This protein required for the 3-processing of the 7S pre-RNA to the mature 5.8S rRNA and has a 3-5 exonuclease activity.