Alignment of the structural template (HCV) and the sequence of GBV-C. Sequence alignment of the HCV polymerase and the GBV-C polymerase. Identical amino acids are boxed in red. We superimposed secondary structure elements from the HCV polymerase in pink, the predicted structural elements of the GBV-C polymerase in blue and the secondary structure element of our final model in black. The HCV numbering according to  is given in pink. The numbering in dark red corresponds to the structure elements which have been observed with a better resolution. The dots in the alignment and structural elements (predicted or average) symbolise gaps. Green letters show universal motifs of RNA polymerases. Green arrows indicate amino acids involved in NTP binding. The green star indicates the amino acid supposed to stack the priming base. The numbering is that of the GBV-C polymerase. Numbers in dark green indicate cysteines involved in a putative disulfide bridge in our model. Residues forming the allosteric GTP binding site are underlined in black.