PCNA N107C was labeled with Cy3 or Cy5 maleimide (GE Healthcare) to a final stoichiometry of 2.7:1 Cy5 to PCNA trimer or 3:1 Cy3 to PCNA trimer. For both labeled proteins, the chemical labeling reactions and free-dye removal steps were carried-out identically as described in Kim et al.46 (link).
Free full text: Click here