![Figure 4.](F4.medium.gif)
CPF/CF IA/CF IB harbors an intrinsic mechanism for controlling pA tail length. (A) Time-course analysis of polyadenylation as in Figure 3B, but by CPF in the presence of both cleavage factors CF IA and CF IB. (B) CPF-synthesized pA tails in the presence of CF IA and CF IB (CFs) and either low (“+”; 250 nM) or high (“++”; 1 µM) concentrations of Pab1p or Nab2p (600 nM). Assays were performed as in Figure 3D. (C) Time-course analysis of polyadenylation by CPF in the presence of either CF IA (left panel) or CF IB (right panel).