ATOX1 (antioxidant 1 copper chaperone) is a cytosolic metallochaperone that delivers cuprous ions (Cu+) to copper ATPases ATP7A and ATP7B, functioning as a critical component of the CTR1-ATOX1-ATP7A/ATP7B copper homeostasis axis 1. The protein binds Cu+ through its conserved CxxC metal-binding motif involving Cys12 and Cys15 residues 2, enabling conformational flexibility for protein-protein interactions and copper transfer to partner proteins including CCS 3. Beyond copper transport, ATOX1 possesses transcription factor activity, regulating genes including CCND1, MDC1, and SOD3, thereby supporting cell proliferation and survival 4. ATOX1 protects cells against oxidative stress through multiple mechanisms: maintaining mitochondrial copper balance, facilitating mitophagy via DJ-1 interaction, and regulating antioxidant enzyme activity 5. Pathologically, ATOX1 dysregulation is implicated in cancer progression through altered copper-dependent signaling and metastatic capacity 4. In lymphoma, ATOX1 overexpression promotes proliferation via MAPK pathway activation in a copper-dependent manner 6. Additionally, ATOX1 oxidation and cisplatin binding influence chemotherapy resistance 7. Copper metabolism dysregulation involving ATOX1 is associated with neurodegenerative diseases, cardiovascular disease, and cancer 18.