Fig. (4) Model of NS5B with a cartoon template RNA.NS5B (pdb code: 2I1R) structure showing the active site located in the palm domain and the regions of the protein that would interact with the RNA in the fingers domain to localize the template tunnel and the β-loop. The β-loop element (Fig 4A) is shown in yellow in the NS5B structure. Figure 4B depicts the same view of the active site without the β-loop.