EXOSC1 is a core component of the exosome. The mammalian exosome is required for rapid degradation of AU rich element-containing RNAs but not for poly(A) shortening. The association of this protein with the exosome is mediated by protein-protein interactions with ribosomal RNA-processing protein 42 and ribosomal RNA-processing protein 46. Recombinant human EXOSC1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.