RMSD plots showing convergence and stability of simulations. Shown is the RMSD, relative to the starting structure, of the active site of our computational model of the POLRMT complex bound by CTP, A, as a function of simulation time. RMSD plots for simulations initiated after replacing the CTP in the active site by ATP or GTP at the end of the MD simulation of the CTP-bound complex are shown in B and C, respectively.