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- Gene: [CP](/genes/cp)
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- UniProt: [P00450](https://www.uniprot.org/uniprot/P00450)
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- Molecular Weight: ~132 kDa
- Subcellular Location: Secreted (plasma), GPI-anchored (brain)
- PDB Structures: [2J5W](https://www.rcsb.org/structure/2J5W), [1KCW](https://www.rcsb.org/structure/1KCW)
Ceruloplasmin is a multi-copper ferroxidase essential for systemic and brain iron metabolism. Synthesized primarily in the liver as a secreted plasma protein, an alternative GPI-anchored form is produced by astrocytes in the brain. CP oxidizes Fe2+ to Fe3+, enabling iron binding to transferrin for transport and preventing iron-mediated oxidative damage through Fenton chemistry.
Ceruloplasmin is the major copper-containing protein in plasma, containing 95% of circulating copper:
- Six copper atoms: Three type I coppers (blue), one type II, two type III
- Three plastocyanin-like domains: Sixfold internal sequence repeat
- Iron-binding sites: Multiple sites for substrate Fe2+ binding
- GPI-anchor site: Alternative C-terminus for membrane attachment in brain
The structure forms a triangular arrangement with a central trinuclear copper cluster essential for ferroxidase activity.
CP catalyzes the oxidation of Fe2+ to Fe3+:
4 Fe2+ + 4 H+ + O2 -> 4 Fe3+ + 2 H2O
This reaction is critical for:
- Iron export: Enables iron loading onto transferrin
- Iron distribution: Supports systemic iron transport
- Antioxidant protection: Removes pro-oxidant Fe2+
GPI-anchored CP on astrocytes plays a unique role:
- Iron efflux from brain: Works with ferroportin to export iron
- Neuronal iron supply: Generates transferrin-bound iron for neurons
- BBB protection: Protects blood-brain barrier from iron toxicity
CP serves as the major copper transport protein:
- Copper delivery: Carries copper to tissues
- Copper storage: Safe copper sequestration
- Redox buffering: Prevents free copper toxicity
Hereditary CP deficiency causes severe neurodegeneration:
- Genetics: Autosomal recessive CP gene mutations
- Clinical triad: Retinal degeneration, diabetes, neurological symptoms
- Brain iron accumulation: Massive iron deposits in basal ganglia
- Onset: Typically 30-50 years of age
- Pathology: Neuronal loss, gliosis, iron-positive inclusions
Copper metabolism disorder with CP involvement:
- Low CP levels: Characteristic diagnostic finding
- Copper-iron interaction: Disrupted iron handling
- Hepatic synthesis: Impaired CP production
CP alterations in AD:
- CSF ceruloplasmin: Decreased levels correlate with severity
- Amyloid binding: CP binds Abeta peptides
- Oxidative stress: Reduced ferroxidase activity increases oxidative damage
- Iron accumulation: Contributes to AD-related iron dysregulation
CP-iron axis in PD:
- Nigral iron accumulation: Exacerbated by low CP activity
- Ferroxidase deficiency: Impaired iron export
- Oxidative stress: Uncontrolled Fe2+ promotes lipid peroxidation
- Dopaminergic vulnerability: High iron demand increases susceptibility
CP dysfunction contributes to NBIA spectrum:
- Secondary aceruloplasminemia: Acquired CP deficiency
- Combined defects: CP-ferroportin complex disruption
- Therapeutic implications: Iron chelation may help
Treatment approaches for aceruloplasminemia:
- Deferoxamine: Variable efficacy
- Deferasirox: Some clinical benefit
- Deferiprone: Brain-penetrant option
For Wilson's disease-related CP issues:
- Copper histidine: May increase holo-CP levels
- Zinc therapy: Reduces copper loading
Emerging approaches:
- AAV-CP delivery: Liver-targeted gene therapy
- Enzyme replacement: Recombinant CP infusion
- Stem cell therapy: Hepatocyte transplantation
CP as a diagnostic marker:
- Wilson's disease screening: Low CP is diagnostic
- Iron status assessment: CP reflects iron handling
- Neurodegeneration marker: Decreased in several conditions
| Interactor |
Relationship |
Functional Relevance |
| Ferroportin |
Iron export complex |
GPI-CP stabilizes ferroportin |
| Transferrin |
Iron transport |
CP loads iron onto transferrin |
| Hephaestin |
Paralog ferroxidase |
Intestinal iron absorption |
| APP |
Ferroxidase activity |
APP has CP-like activity |
| Copper ATPases |
Copper loading |
ATP7A/B incorporate copper |
- UniProt - Protein sequence and functional data
- PubMed - Biomedical literature
- PDB - Protein structure data