Accepts the ubiquitin-like protein NEDD8/RUB1 from the UBA3-ULA1 E1 complex and catalyzes its covalent attachment to other proteins. The major substrate is CDC53/Cullin. [E1 NEDD8-activating enzyme]-S-[NEDD8 protein]-yl-L-cysteine + [E2 NEDD8-conjugating enzyme]-L-cysteine = [E1 NEDD8-activating enzyme]-L-cysteine + [E2 NEDD8-conjugating enzyme]-S-[NEDD8-protein]-yl-L-cysteine. Protein modification; protein neddylation. Interacts with DCN1. The acetylation of Met-1 is cotranslational, and not regulatory. The N-acetylmethionine increases affinity for DCUN1D1 by about 2 orders of magnitude and is crucial for NEDD8 transfer to cullins. Belongs to the ubiquitin-conjugating enzyme family. UBC12 subfamily.