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 and may play a role in the cell cycle progression by regulating the SCF ubiquitin E3 ligase complex, after UV damage. At the cell membrane, can promote and as well inhibit cullins neddylation. Part of a complex containing DCUN1D3, CUL3 and RBX1. Interacts (via the DCUN1 domain) with the unneddylated cullins: interacts with CUL1, CUL2, CUL3, CUL4A, CUL4B and CUL5; these interactions promote the cullin neddylation and the identity of the cullin dictates the affinity of the interaction. Interacts preferentially with CUL3; this interaction triggers the relocalization of CUL3 to the cell membrane where CUL3 is neddylated. Interacts (via DCUN1 domain) with RBX1. May also interact with regulators or subunits of cullin-RING ligases such as RNF7, ELOB and DDB1; these interactions are bridged by cullins. Interacts (via DCUN1 domain) with CAND1; this interaction is bridged by cullins and strongly inhibits cullin neddylation. These CAND-cullin-DCNL complexes can only be neddylated in the presence of a substrate adapter. Interacts (via DCUN1 domain) with the N-terminally acetylated form of UBE2M and UBE2F. After UVC treatment, the protein enters to the nucleus gradually. Cell membrane localization is essential for CUL3 neddylation. The DCUN1 domain, also known as PONY domain, mediates the interaction with different cullins. The DCUN1 domain mediates the interaction with the N-terminally acetylated NEDD8-conjugating E2s enzyme leading to the NEDD8 transfer from N-terminally acetylated NEDD8-conjugating E2s enzyme to different cullin C-terminal domain-RBX complexes; the neddylation efficiency correlates with the DCUN1D5-cullin and DCUN1D5-E2 interaction affinities. This domain is also involved in CAND1-, cullins- and RBX1-binding.