fig2

Figure 2. The signaling pathways of copper metabolism. Extracellular Cu²⁺ is reduced to Cu⁺ via STEAP. Both Cu²⁺ and Cu⁺ are transported into cells via corresponding transporters. Intracellular copper is sequestrated via MT1/2 or GSH or transported via COX17, CCS, SOD1, ATOX1, MEMO1, and ATP7B. Mitochondrial copper functions via SCO1, SCO2, MT-CO1, MT-CO2, and COX11, while nuclear copper can regulate gene expression. STEAP: 6-Transmembrane epithelial antigen of prostate, comprises STEAP1, STEAP2, STEAP3 and STEAP4; MT1/2: metallothionein 1/2; GSH: glutathione; COX17: cytochrome c oxidase copper chaperone COX17; CCS: copper chaperone for superoxide dismutase; SOD1: superoxide dismutase 1; ATOX1: antioxidant 1 copper chaperone; MEMO1: mediator of cell motility 1; ATP7B: ATPase copper-transporting beta; SCO1: synthesis of cytochrome C oxidase 1; SCO2: synthesis of cytochrome C oxidase 1; MT-CO1: mitochondrially encoded cytochrome c oxidase I; MT-CO2: mitochondrially encoded cytochrome c oxidase II; COX11: cytochrome c oxidase copper chaperone COX11.