{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Copper chaperone for superoxide dismutase (CCS) is a multifunctional protein that is essential for the precise delivery of copper to its target enzymes and for maintaining proper copper homeostasis in the cell. One of its best‐characterized functions is to facilitate the incorporation of copper into copper/zinc superoxide dismutase (SOD1), an important antioxidant enzyme. Through a highly coordinated, multi‐domain mechanism, CCS initially acquires Cu(I) via its N‐terminal domain, then associates with SOD1 through its central region to “present” copper, and finally catalyzes the formation of an intramolecular disulfide bond via its C-terminal domain, thus ensuring proper SOD1 folding and activity."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "4"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Moreover, CCS is not only pivotal for SOD1 activation but also plays additional roles in copper‐dependent cellular processes. For instance, CCS is required for hypoxia‐inducible factor 1 (HIF-1) activation under low oxygen conditions, where its activity depends on copper availability."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": " In another context, CCS has been shown to interact with the inhibitor of apoptosis protein XIAP, with this interaction enhancing its chaperone activity toward SOD1, thereby linking copper delivery to anti‐apoptotic signaling."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Structural and mutagenesis studies have revealed that specific cysteine motifs in CCS are critical for copper binding and cluster formation. These motifs enable CCS to form multinuclear copper clusters that are required for efficient copper transfer and disulfide formation in SOD1."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": " Additionally, alterations in CCS’s cysteine residues or its domain structure markedly impair its ability to activate SOD1, leading to defective antioxidant defense and potential contributions to neurodegenerative pathologies such as amyotrophic lateral sclerosis (ALS)."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "9"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Beyond its cytosolic role, CCS has been implicated in mitochondrial copper regulation. Studies indicate that CCS contributes to copper delivery into mitochondria and may act as part of an import mechanism for SOD1 into the intermembrane space, although it does not directly mediate cytochrome c oxidase copper loading."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "10"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Finally, cellular copper levels themselves regulate CCS post-translationally; under conditions of copper sufficiency, CCS protein abundance is reduced, whereas copper deficiency or interference with copper delivery systems leads to its accumulation. This autoregulatory mechanism helps balance copper homeostasis and prevent toxic free copper accumulation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "12"}]}, {"type": "t", "text": " In neuronal cells, interactions between CCS and adaptor proteins (such as the PDZ domains of X11α) further highlight the complex network by which CCS integrates copper biochemistry with broader cellular signaling pathways."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "14"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n In summary, CCS is a critical mediator of cellular copper metabolism. It ensures the proper metallation and stabilization of SOD1 through a sophisticated, domain-driven mechanism, while also influencing copper-dependent signaling pathways, mitochondrial copper homeostasis, and cellular responses to oxidative stress. Disruption of CCS function, whether by mutation or altered copper availability, can have significant pathological consequences.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Lucia Banci, Ivano Bertini, Francesca Cantini, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Human superoxide dismutase 1 (hSOD1) maturation through interaction with human copper chaperone for SOD1 (hCCS)."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Proc Natl Acad Sci U S A (2012)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1073/pnas.1207493109"}], "href": "https://doi.org/10.1073/pnas.1207493109"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "22869735"}], "href": "https://pubmed.ncbi.nlm.nih.gov/22869735"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Jay P Stasser, John F Eisses, Amanda N Barry, et al. 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