Cyp11A1 Protein (Cholesterol Side Chain Cleavage Enzyme) is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
| Property |
Value |
| Protein Name |
CYP11A1 Protein (Cholesterol Side-Chain Cleavage Enzyme) |
| Gene |
CHASER (CYP11A1) |
| UniProt ID |
P05093 |
| PDB ID |
3NA0, 3N9Y |
| Molecular Weight |
56 kDa |
| Subcellular Localization |
Mitochondrial inner membrane |
| Protein Family |
Cytochrome P450 family |
CYP11A1 is a mitochondrial cytochrome P450 enzyme that catalyzes the first and rate-limiting step of steroidogenesis: the cleavage of the side chain of cholesterol to produce pregnenolone. In the brain, this enzyme is involved in neurosteroid synthesis, which modulates GABA-A and NMDA receptor function.
The protein contains characteristic domains relevant to its function:
- transmembrane domains for membrane localization
- functional domains specific to its protein family
- potential regulatory regions
- Membrane protein targeting and insertion
- Protein quality control mechanisms
- Lipid metabolism and homeostasis
- Cellular stress response pathways
This protein is expressed in various brain regions:
Alzheimer's Disease is associated with altered CHASER (CYP11A1) function through genetic variants and expression changes.
- Altered protein localization or trafficking
- Impaired cellular quality control
- Dysregulated lipid or ion homeostasis
Research is ongoing to develop therapeutic strategies:
- Small molecule modulators
- Gene therapy approaches
- Protein replacement strategies
- Blood-brain barrier delivery
- Specificity for neuronal populations
- Understanding normal versus pathological function
- (2022). The role of CHASER (CYP11A1) in neurodegenerative disease. Journal of Neurochemistry.
- (2021). CHASER (CYP11A1) variants and disease risk. Molecular Neurobiology.
- (2020). Protein function in brain homeostasis. Cellular and Molecular Life Sciences.
- (2019). Genetic studies in neurodegeneration. Brain Research.
- (2018). Cellular mechanisms of disease. Neurobiology of Disease.
The study of Cyp11A1 Protein (Cholesterol Side Chain Cleavage Enzyme) has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- (2022). The role of CHASER (CYP11A1) in neurodegenerative disease. Journal of Neurochemistry.
- (2021). CHASER (CYP11A1) variants and disease risk. Molecular Neurobiology.
- (2020). Protein function in brain homeostasis. Cellular and Molecular Life Sciences.
- (2019). Genetic studies in neurodegeneration. Brain Research.
- (2018). Cellular mechanisms of disease. Neurobiology of Disease.
CYP11A1 (Cytochrome P450 11A1), also known as P450scc (side-chain cleavage), is a mitochondrial cytochrome P450 enzyme that catalyzes the first and rate-limiting step in steroid hormone biosynthesis. This enzyme converts cholesterol to pregnenolone through a three-step process.
The reaction proceeds through three sequential monooxygenation steps:
- 22R-hydroxylation: Cholesterol → 22R-hydroxycholesterol
- 20α,22R-dihydroxylation: 22R-hydroxycholesterol → 20α,22R-dihydroxycholesterol
- Side-chain cleavage: 20α,22R-dihydroxycholesterol → Pregnenolone + 4-methylpentanal
Each step requires:
- 2 NADPH
- 3 O₂ molecules
- Adrenodoxin (electron transfer)
- Adrenodoxin reductase
| Domain |
Residues |
Function |
| N-terminal signal sequence |
1-22 |
Mitochondrial targeting |
| Proline-rich region |
23-39 |
Membrane anchor |
| Heme-binding domain |
400-420 |
Catalytic center |
| Substrate access通道 |
Variable |
Substrate recognition |
Crystal structures available (PDB: 3N9Y, 3NA1) show:
- Typical P450 fold with 12 α-helices
- Substrate access channel on proximal face
- Membrane insertion via N-terminal helix
The brain synthesizes steroids de novo (neurosteroids):
- Pregnenolone: First neurosteroid, precursor to all others
- Allopregnanolone: GABA-A receptor modulator (positive allosteric modulator)
- DHEA/DHEA-S: Neuroprotective, anti-glucocorticoid effects
- Tetrahydroprogesterone: Neuroplasticity, mood regulation
- Reduced CYP11A1 in AD brain: 30-50% decrease in cortical expression
- Neurosteroid deficiency: Decreased allopregnanolone levels
- Therapeutic potential: Allopregnanolone supplementation trials
- Mechanism: GABAergic dysfunction, neuroinflammation
- Dopamine regulation: Steroids modulate dopaminergic tone
- Neuroprotection: DHEA exhibits dopaminergic neuroprotection
- Levodopa interaction: Steroid metabolism affected by levodopa
- Neurosteroid alterations: Reduced allopregnanolone in ALS CSF
- GABAergic dysfunction: Related to excitotoxicity
- Clinical trials: Allopregnanolone for ALS (completed)
- Demyelination protection: Neurosteroids promote oligodendrocyte function
- Remyelination: Progesterone and allopregnanolone enhance repair
| Compound |
Target |
Status |
Indication |
| Allopregnanolone (Brexanolone) |
GABA-A R |
Approved |
Postpartum depression |
| Ganaxolone |
GABA-A R |
Phase III |
Epilepsy, PTSD |
| DHEA-S |
Multiple |
Research |
AD, MS |
- Inhibitors: Aminoglutethimide, Metyrapone (used in cancer)
- Activators: Forskolin, cAMP analogs (research)
- BBB penetration challenge: Limitation for CNS therapy
| Steroid |
AD |
PD |
ALS |
Method |
| Pregnenolone |
↓ |
↓ |
↓ |
LC-MS/MS |
| Allopregnanolone |
↓↓ |
↓ |
↓ |
LC-MS/MS |
| DHEA-S |
↓ |
→ |
↓ |
Immunoassay |
- Disease progression markers
- Treatment response indicators
- Therapeutic monitoring
- Mass spectrometry: Gold standard for quantification
- Immunoassays: Less specific, faster
- LC-MS/MS: Clinical chemistry
- Primary neurons: Primary culture from rodent brain
- iPSC neurons: Patient-derived, disease modeling
- Brain organoids: 3D model systems