Abstract
In eukaryotes, RNA polymerase II is responsible for the transcription of the precursors of messenger RNA, which undergo an extensive co-transcriptional processing whose final result is their maturation. Except for the transcripts of histone genes, the precursors of every other messenger RNAs present endonucleolytic cleavage and polyadenylation at their 3' ends. Notably, the cleavage/ poly…