Figure 2. Example of a crucial structural element that is not conserved in the consensus sequence motifs.

a | The overlay of the crystal structures of hepatitis C virus (HCV) helicase (red; PDB code: 1HEI) and PcrA helicase (cyan; PDB code: 1QHH). The ATP is coloured magenta. The HCV helicase has three domains, whereas the PcrA helicase has four domains. The overlay shows the overall structural homology of three domains of the two structures, although they share very little sequence similarity. b | Identification of a conserved functional element in motif VI and IV by structure in HCV RNA Helicase and PcrA DNA helicase