CstF CF II CF I Mature intronless derived mRNA complex intronless pre-mRNA cleavage complex Cleavage and polyadenylation of Intronless Pre-mRNA Authored: Wahle, E, 2003-06-05 08:30:31 Edited: Gillespie, ME, 0000-00-00 00:00:00 Pubmed10371034 Reactome Database ID Release 4377593 Reactome, http://www.reactome.org ReactomeREACT_45 The nuclear poly(A) binding protein (PABPN1), which binds the growing poly(A) tails once it has reached a length of about ten nucleotides. Stimulation of poly(A) polymerase by both CPSF and PABPN1 is synergistic and results in processive elongation of the RNA (the polymerase adds AMP residues without dissociating from the RNA). The processive reaction is terminated when the tail has reached a length of about 250 nucleotides.