Exosome complex component CSL4 (Exosome component 1)
1_MAPPV 6_ RYCIP 11_ GERLC 16_ NLEEG 21_ SPGSG 26_ TYTRH 31_ GYIFS 36_ SLAGC 41_ LMKSS 46_ ENGAL 51_ PVVSV 56_ VRETE 61_ SQLLP 66_ DVGAI 71_ VTCKV 76_ SSINS 81_ RFAKV 86_ HILYV 91_ GSMPL 96_ KNSFR 101_ GTIRK 106_ EDVRA 111_ TEKDK 116_ VEIYK 121_ SFRPG 126_ DIVLA 131_ KVISL 136_ GDAQS 141_ NYLLT 146_ TAENE 151_ LGVVV 156_ AHSES 161_ GIQMV 166_ PISWC 171_ EMQCP 176_ KTHTK 181_ EFRKV 186_ARVQP
1: 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 may 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, the RNA exosome complex is involved 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, preventing translation of aberrant 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 of RNA for ribonucleolysis, and to serve as a scaffold for the association with catalytic subunits and accessory proteins or complexes. EXOSC1 as peripheral part of the Exo-9 complex stabilizes the hexameric ring of RNase PH-domain subunits through contacts with EXOSC6 and EXOSC8