(B) The 39-kDa catalytic domain (8-kDa subdomain not shown for clarity) is colored by subdomain: fingers (salmon), palm (yellow) and thumb (purple). The polymerase is in complex with a 1-nt gapped 16-mer oligo (grey) containing a templating 8-oxo-dG (green). Key residues involved in stabilizing the templating base (Y505 and R517) are shown in black. 