The function of DCUN1D4 (defective in cullin neddylation 1 domain containing 4, Ensembl gene identifier ENSG00000109184) is as follows. Contributes to the neddylation of all cullins by transferring NEDD8 from N-terminally acetylated NEDD8-conjugating E2s enzyme to different cullin C-terminal domain-RBX complexes which are necessary for the activation of cullin-RING E3 ubiquitin ligases (CRLs). .