The exosome is a conserved complex which identified in Saccharomyces cerevisiae and has 3′ exoribonuclease activity in vitro. The exosome contains ten core subunits, and all except Csl4p/Ski4p are 3′ exoribonucleases in vitro. The exosome acts important role in several pathways of RNA metabolism. The exosome is a universal complex in eukaryote and is related to expression of eukaryotic genes.