PolyA addition - 3’ Polyadenylation

1.Polyadenylation starts when RNA Pol II has transcribed the end of the gene –marked by AAUAAA 2.AAUAAA bound by CPSF 3.The CA sequence is bound by CFII 4.GU-rich sequence beyond the cleavage site is bound by CstF Cleavage follows: AAUAAA - PAP bond breaks, Add ATP and remove the GU sequence, ends up with AAAOH3, Add PABII (Adds A in between A and OH), Add more ATP to add more As