NEDD8 trimers specifically bind to the second zinc finger of PARP-1. NEDP1 KO U2OS cells were transfected with GFP, GFP-PARP-1, or with GFP fused to the Zn1 domain (AA 1-96), the Zn2 domain (AA 97-215), the Zn3 domain (AA 216-336) or the Zn1+2 domains (AA 1-215) of PARP-1. 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. 