EXOSC9
Description
The EXOSC9 (exosome component 9) is a protein-coding gene located on chromosome 4.
Exosome component 9, also known as EXOSC9, is a human gene. Its protein product (sometimes called RRP45 or PM/Scl-75) is part of the exosome complex and is an autoantigen in patients with certain autoimmune diseases, most notably scleromyositis.
EXOSC9 is a non-catalytic component of the RNA exosome complex, which has 3'-to-5' exoribonuclease activity and plays a crucial role in various cellular RNA processing and degradation events. In the nucleus, it participates in the proper maturation of stable RNA species such as rRNA, snRNA, and snoRNA, the elimination of RNA processing by-products and non-coding transcripts like antisense RNA species and promoter-upstream transcripts (PROMPTs), and the degradation of mRNAs with processing defects, thereby limiting their export to the cytoplasm. The RNA exosome may also be 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, EXOSC9 is involved in general mRNA turnover, specifically degrading inherently unstable mRNAs containing AU-rich elements (AREs) within their 3' untranslated regions. It also participates in RNA surveillance pathways, preventing translation of aberrant mRNAs and potentially degrading histone mRNA. As a component of the catalytically inactive RNA exosome core (Exo-9) complex, EXOSC9 is proposed to play a pivotal role in binding and presenting RNA for ribonucleolysis and acts as a scaffold for the association with catalytic subunits and accessory proteins or complexes. EXOSC9 directly binds to ARE-containing RNAs.
EXOSC9 is also known as PCH1D, PM/Scl-75, PMSCL1, RRP45, Rrp45p, p5, p6.
