Figure 7.

Polε has a steric gate for the 2′-hydroxyl of a primer. The protein is represented as cartoon and colored cyan; Thr876 is shown as sticks. The template and primer are shown as sticks and colored blue for nitrogen, red for oxygen, orange for phosphorus, and grey for carbon. The O1 of Thr876 and modeled O2 of primer Cyt are presented as spheres with 60% transparency and colored red. The interception of spheres indicates steric hindrance. The crystal structure of the ternary complex of yeast Polε_CD with DNA and dCTP (pdb code 6hiv (22)) was used for this presentation prepared with the PyMOL Molecular Graphics System.