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 cryptic unstable transcripts (CUTs), and of mRNAs with processing defects, thereby limiting or excluding their export to the cytoplasm. In the cytoplasm, the RNA exosome complex is involved in general mRNA turnover and in RNA surveillance pathways, preventing translation of aberrant mRNAs. 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. DIS3 has both 3'-5' exonuclease and endonuclease activities. The exonuclease activity of DIS3 is down-regulated upon association with Exo-9 possibly involving a conformational change in the catalytic domain and threading of the RNA substrate through the complex central channel. Structured substrates can be degraded if they have a 3' single-stranded extension sufficiently long (such as 35 nt poly(A)) to span the proposed complex inner RNA-binding path and to reach the exonuclease site provided by DIS3. Plays a role in mitotic control. Component of the RNA exosome complex. The catalytically inactive RNA exosome core (Exo-9) complex which is believed to associate with catalytic subunits DIS3 and RRP6 in cytoplasmic- and nuclear-specific RNA exosome complex forms. Exo-9 is formed by a hexameric ring of RNase PH domain-containing subunits and peripheral S1 domain-containing components CSL4, RRP4 and RRP40 located on the top of the ring structure. DIS3 associates at the respective bottom side with Exo-9. Interacts with GSP1. Present with 606 molecules/cell in log phase SD medium. Mn(2+) doesn't support the hydrolytic activity. Activity is KCl or NaCl dependent and activity is slightly increased in the presence of reducing agents such as DTT or beta-mercaptoethanol and doesn't vary notably between pH 6.8 and 8.8. Belongs to the RNR ribonuclease family. It was originally thought that there are multiple subunits in the exosome that have exonuclease activity but it was later shown (PubMed:17173052 and PubMed:17174896) that only this DIS3/RRP44 subunit of the exosome core has this activity.