This family of proteins are components of the exosome 3'->5' exoribonuclease complex. The exosome mediates degradation of unstable mRNAs that contain AU-rich elements (AREs) within their 3' untranslated regions .
Exosome is a complex of 3' --> 5' exoribonucleases that play a major role in diverse RNA processing and degradation pathways. The eukaryotic exosome complex contains 9 proteins. Six RNase PH domain containing proteins (Rrp41, Rrp42, Rrp43, Rrp45, Rrp46, and Mtr3) form a catalytic ring, three RNA binding domain containing proteins (Rrp4,Rrp40, and Csl4) bind on top of the ring [PUBMED:17174896].