Competition of SUMO-1 DNA interaction by TDG N-terminus. GST-SUMO-1 DNA complexes were incubated with increasing amounts of free SUMO-1, the TDG N-terminus or GST for the UV-crosslinking experiments carried out under the conditions described for Figure 3. The double stranded oligonucleotide used was the 65-mer. "Control" refers to the GST-SUMO-1 alone. Roughly 2 and 5 molar excess of competitor proteins were used.