#Id: 6661
#Unit 3. Fundamental Processes
The site of cleavage/polyadenylation in most pre-mRNAs is flanked by two cis-acting signals: An upstream AAUAAA motif, which is usually located 11 to 30 nucleotides from the site, and A downstream U-rich or GU-rich element.
he AAUAAA is needed for cleavage and polyadenylation because deletion or mutation of the AAUAAA hexamer prevents generation of the polyadenylated 3’ end
