This gene product constitutes one of the subunits of the multisubunit particle called exosome, which mediates mRNA degradation. The composition of human exosome is similar to its yeast counterpart. This protein is homologous to the yeast Mtr3 protein. Its exact function is not known, however, it has been shown using a cell-free RNA decay system that the exosome is required for rapid degradation of unstable mRNAs containing AU-rich elements (AREs), but not for poly(A) shortening. The exosome does not recognize ARE-containing mRNAs on its own, but requires ARE-binding proteins that could interact with the exosome and recruit it to unstable mRNAs, thereby promoting their rapid degradation. [provided by RefSeq, Jul 2008]