DDA1 (DET1 and DDB1 associated 1) functions as a critical scaffolding subunit within DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes 12. DDA1 stabilizes these multiprotein complexes required for ubiquitination and proteasomal degradation of target proteins 34. Structurally, DDA1 associates with DET1 and DDB1 to regulate cullin-4-based E3 ligase activity, with dynamic DDA1-mediated conformational changes in DET1 facilitating recruitment of ubiquitin-conjugating enzymes 5. DDA1 coordinates ubiquitination dynamics in transcription-coupled nucleotide excision repair, enabling efficient turnover and progression of TC-NER processes 6. Disease relevance encompasses multiple malignancies. DDA1 is upregulated in lung cancer, associated with poor prognosis and promoting cell cycle progression through cyclin D1/D3/E1 regulation 7. In ovarian cancer, NR2F6 upregulates DDA1, correlating with worse overall and recurrence-free survival 8. In acute myeloid leukemia, the HOTTIP/microRNA-608/DDA1 axis promotes proliferation and cell cycle progression 9. DDA1 overexpression in breast cancer promotes cisplatin resistance via STAT3 signaling, reversible by dihydroartemisinin treatment 10. Clinically, DET1 mutations cause developmental lethality in humans and neurological defects in mice, highlighting DDA1-containing complexes' essential roles in development 11.