The biochemistry of polyadenylation

During the synthesis of mRNA in the nucleus, 3'-ends are generated by endonucleolytic cleavage followed by polyadenylation. The machinery responsible for this simple reaction is surprisingly complex. In vitro reconstitution of 3'-end processing has demonstrated the importance of cooperative interactions in RNA recognition and catalysis. However, the inventory of processing factors is still incomplete and important mechanistic questions have not yet been answered.