Part of an E3 ubiquitin ligase complex for neddylation. Promotes neddylation of cullin components of E3 cullin-RING ubiquitin ligase complexes (By similarity). Acts by binding to cullin-RBX1 complexes in the cytoplasm and promoting their nuclear translocation, enhancing recruitment of E2-NEDD8 (UBE2M-NEDD8) thioester to the complex, and optimizing the orientation of proteins in the complex to allow efficient transfer of NEDD8 from the E2 to the cullin substrates. Involved in the release of inhibitory effets of CAND1 on cullin-RING ligase E3 complex assembly and activity (By similarity). Acts also as an oncogene facilitating malignant transformation and carcinogenic progression (PubMed:20563250). Part of an E3 complex for neddylation composed of cullins, RBX1, UBE2M and CAND1. 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. Binds neddylated CUL1. Interacts (via the C-terminus 50 AA) directly with RBX1. Interacts (via DCUN1 domain) with the N-terminally acetylated form of UBE2M and UBE2F. Interacts preferentially with UBE2M-NEDD8 thioester (via N-terminus 1-26 AA) than with free UBE2M. UBE2M N-terminal acetylation increases the affinity of this interaction by about 2 orders of magnitude. Interacts with CAND1; this interaction is indirect and is bridged by cullins such as CUL1 and CUL3. May also interact with regulators or subunits of cullin-RING ligases such as RNF7, ELOB and DDB1; these interactions are bridged by cullins. Component of VCB complex that contains at least DCUN1D1, CUL2 and VHL; this complex triggers CUL2 neddylation and consequently cullin ring ligase (CRL) substrates polyubiquitylation. Interacts with VHL; this interaction triggers engagement of HIF1A in the VCB complex and is independent of CUL2. Interacts with CUL2 independently of VHL. Interacts with SOCS1 and SOCS2. Interacts with HIF1A; this interaction increases the interaction between VHL and DCUN1D1. Interacts (via UBA-like domain) with ARIH2; promotes DCUN1D1 ubiquitination. The ubiquitinated form is localized in the cytoplasm. Highly expressed in testis. Also expressed in brain, heart, liver, skeletal muscle and kidney. In brain, preferentially expressed in the telencephalon ventricular and subventricular zones, albeit at low levels. In adult testis, expressed in cells above seminiferous tubules, but only weakly in spermatogonia. Expressed in the developing forebrain, midbrain and hindbrain at early stages of neuronal development. 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 DCUN1D1-cullin and DCUN1D1-E2 interaction affinities. The UBA-like domain mediates interaction with autoubiquitylated ARIH2 leading to ubiquitin ligation to DCUN1D1. Mono- and poly-ubiquitinated by ARIH2 and ARIH1. Monoubiquitination by ARIH2 is mediated by an interaction between autoubiquitinated ARIH2 and the UBA-like domain. The monoubiquitinated form preferentially interacts with non-neddylated cullins and modulates cullin RING ligase (CRL) complex composition and activity.