NEDD8 trimers bind to the DNA-binding domain of PARP-1 (Zn1-3) but not to its automodification and catalytic domain (CAT). NEDP1 KO U2OS cells were transfected with GFP, GFP-PARP-1, GFP fused to the DNA-binding domain of PARP-1 (AA 1-336) or with GFP fused to the PARP-1 automodification and catalytic domain (AA 336-1014). 24 hours post transfection, cell lysates were collected and immunoprecipitation with GFP-Trap was performed. Bound proteins were eluted and resolved by SDS-PAGE analysis, followed by Western blot analysis with the indicated antibodies. 