Yeast nuclear RNA processing

Figure 6 Schematic representation of the basic mode of operation of the 3′→5′ RNA exosome. The figure highlights the need for a cofactor to stimulate the exonuclease activity of the exosome and the need for an RNA helicase to remove secondary structure to allow proper processing or degradation. The figure shows a representative stem loop structured RNA but any RNA with secondary structure could undergo the same remodeling to complete processing or degradation. The cofactor shown is a representative of all known and unknown cofactors. The exosome shows weak exonuclease activity in vitro, yet rapid degradation is seen in vivo, indicating that cofactors are required for this activity[76,80].