| B-Raf Proto-Oncogene, Serine/Threonine Kinase | |
|---|---|
| Gene Symbol | BRAF |
| Full Name | B-Raf Proto-Oncogene, Serine/Threonine Kinase |
| Chromosomal Location | 7q34 |
| NCBI Gene ID | 673 |
| Ensembl ID | ENSG00000157764 |
| UniProt ID | P15056 |
| OMIM ID | 164757 |
| Protein Length | 766 amino acids |
| Protein Family | RAF family, MAP kinase kinase kinases |
| Aliases | RAF1, B-Raf, p94 |
| Associated Diseases | [Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease), Melanoma, Cardiofaciocutaneous Syndrome, Noonan Syndrome |
BRAF (B-Raf proto-oncogene, serine/threonine kinase) is the most potent member of the RAF family of serine/threonine protein kinases that function as critical components of the RAS-RAF-MEK-ERK (MAPK) signaling pathway. BRAF is the strongest activator of MEK1/2 among the three RAF isoforms (ARAF, BRAF, RAF1) due to its higher basal kinase activity and less stringent activation requirements [1].
In the central nervous system, BRAF plays essential roles in neuronal development, synaptic plasticity, memory formation, and cellular stress responses. Dysregulation of BRAF signaling is implicated in neurodegenerative diseases including Alzheimer's disease and Parkinson's disease, as well as various cancers, particularly melanoma where the V600E mutation is the most common oncogenic driver [2].
BRAF contains several functional domains [3]:
BRAF Protein Structure
N-terminus ───────────────────────────────────────── C-terminus
│ │ │ │
▼ ▼ ▼ ▼
┌──────┐ ┌─────────┐ ┌─────────┐ ┌─────────┐
│CR1 │ │ CR2 │ │ CR3 │ │Kinase │
│Region │ │ regulatory│ │ C3 │ │Domain │
└──────┘ └─────────┘ └─────────┘ └─────────┘
│ │ │ │
│ │ │ │
S/T rich Phosphorylation Zinc finger Catalytic
domain sites (S151, domain kinase
T598, S729) activity
BRAF activation requires multiple steps [4][3:1]:
| Feature | BRAF | RAF1 (CRAF) | ARAF |
|---|---|---|---|
| Kinase activity | Highest | Intermediate | Lowest |
| MEK activation | Potent | Moderate | Weak |
| Dimerization | Strong | Strong | Weak |
| Neuronal expression | High | High | Lower |
| Oncogenic potential | High | Low | Low |
BRAF/MAPK signaling is dysregulated in AD through multiple mechanisms [5][6]:
The balance between physiological BRAF signaling (required for memory) and pathological overactivation (causing neurodegeneration) is critical.
In PD, BRAF contributes to disease pathogenesis through [7]:
BRAF-mediated MAPK signaling is crucial for synaptic plasticity [8][9]:
BRAF in Synaptic Plasticity
Neurotrophic factor (BDNF, NGF)
│
▼
RTK activation
│
▼
RAS-GTP formation
│
▼
RAF activation (BRAF/RAF1)
│
▼
MEK1/2 activation
│
▼
ERK1/2 activation
│
├──────────► Transcription (CREB)
│ │
│ ▼
│ Synaptic protein synthesis
│ │
│ ▼
│ LTP/LTM formation
│
└──────────► Synaptic remodeling
(actin cytoskeleton)
BRAF is essential for neural development [10][11]:
In neurons, BRAF signaling mediates cellular stress responses:
BRAF is widely expressed in the central nervous system:
| Region | Expression Level | Cell Types |
|---|---|---|
| Cortex | High | Pyramidal neurons, interneurons |
| Hippocampus | High | CA1-CA3 pyramidal cells, granule cells |
| Cerebellum | High | Purkinje cells, granule cells |
| Substantia nigra | Moderate | Dopaminergic neurons |
| Thalamus | Moderate | Relay neurons |
| Spinal cord | Moderate | Motor neurons, interneurons |
Therapeutic targeting of BRAF in neurodegeneration requires careful consideration [12]:
BRAF inhibitors (vemurafenib, dabrafenib)
MEK inhibitors (trametinib, selumetinib)
ERK inhibitors
| Partner | Interaction Type | Function |
|---|---|---|
| RAS family | Activator | Membrane recruitment and activation |
| RAF1 | Dimerization partner | Heterodimer formation |
| MEK1 | Substrate | Phosphorylation |
| MEK2 | Substrate | Phosphorylation |
| 14-3-3 proteins | Binding | Sequestration, inactive complex |
| KSR1/2 | Scaffold | Pathway assembly |
The V600E mutation is the most common BRAF oncogenic variant [2:1]:
BRAF germline mutations cause [13]:
BRAF/MAPK activation status: