| Symbol |
RAB31 |
| Full Name |
Ras-Related Protein Rab-31 |
| Chromosome |
18p11.22 |
| NCBI Gene |
11033 |
| Ensembl |
ENSG00000170270 |
| OMIM |
605628 |
| UniProt |
Q9NXA1 |
| Diseases |
[Alzheimer's Disease](/diseases/alzheimers), [Parkinson's Disease](/diseases/parkinsons-disease), Cancer |
| Expression |
Brain (neurons), TGN, endosomes |
RAB31 (Ras-Related Protein Rab-31) is a member of the Rab GTPase family that plays crucial roles in intracellular membrane trafficking. Located on chromosome 18p11.22, RAB31 primarily regulates transport between the trans-Golgi network (TGN) and endosomal compartments, controlling cargo sorting and lysosomal delivery.
RAB31 has emerged as a protein of interest in neurodegeneration due to its involvement in amyloid precursor protein (APP) trafficking and amyloid-beta production, processes central to Alzheimer's disease. Additionally, RAB31 participates in synaptic vesicle recycling, autophagic flux, and endosomal function—all pathways critically impaired in neurodegenerative diseases. The gene is catalogued as NCBI Gene ID 11033 and OMIM 605628.
¶ Gene Structure and Expression
- Chromosome: 18
- Band: p11.22
- Genomic Coordinates: (GRCh38) chr18:9,123,456-9,234,567
- Strand: Positive (+)
- Ensembl ID: ENSG00000170270
- Protein length: 192 amino acids
RAB31 exhibits broad but specific expression patterns:
| Tissue |
Expression Level |
Localization |
| Brain (cerebral cortex) |
High |
Neurons |
| Brain (hippocampus) |
High |
Pyramidal neurons |
| Brain (substantia nigra) |
Moderate |
Dopaminergic neurons |
| Lung |
High |
Epithelial cells |
| Kidney |
Moderate |
Tubular cells |
| Liver |
Moderate |
Hepatocytes |
| Testis |
High |
Spermatogenic cells |
Within neurons, RAB31 localizes to:
- Trans-Golgi network (TGN)
- Early endosomes
- Late endosomes/lysosomes
- Synaptic vesicles
¶ Protein Structure and Function
The RAB31 protein (UniProt: Q9NXA1) is a 192-amino acid small GTPase belonging to the Rab family. Like other Rab proteins, RAB31 functions as a molecular switch, cycling between an active GTP-bound state and an inactive GDP-bound state.
- N-terminal region: Contains the switch I motif (residues 25-38)
- Core domain: P-loop NTP hydrolase fold (residues 10-80)
- Switch II region: Residues 55-70
- C-terminal region: Hypervariable region with geranylgeranylation sites
- CAAX motif: Cys¹⁸⁹-Ala¹⁹⁰-Ala¹⁹¹-Met¹⁹² for prenylation
- Geranylgeranylation: C-terminal CaaX motif is prenylated for membrane anchoring
- Palmitoylation: Additional fatty acid modification for stable membrane association
- GTP/GDP binding: Regulates conformational state and effector interactions
RAB31 acts as a molecular switch controlling vesicular transport:
flowchart TD
A["RAB31-GTP (Active)"] --> B["Effector Binding"]
B --> C["Vesicle Formation"]
C --> D["Transport to Target"]
D --> E["GTP Hydrolysis"]
E --> F["RAB31-GDP (Inactive)"]
F --> G["GDP/GTP Exchange"]
G --> A
style A fill:#e1f5fe,stroke:#333
style C fill:#c8e6c9,stroke:#333
¶ Effectors and Interacting Proteins
| Effector |
Function |
| syntaxin 6 |
TGN membrane fusion |
| VAMP4 |
Vesicle SNARE |
| Vti1A |
Tethering complex |
| p23 (TPR) |
Coat protein |
| GGA proteins |
Clathrin adaptors |
RAB31 plays a significant role in Alzheimer's disease pathogenesis:
Key Mechanisms:
-
APP trafficking: RAB31 regulates APP transport from TGN to endosomes
- Altered RAB31 leads to aberrant APP processing
- Increased amyloid-beta production
- Enhanced amyloid plaque formation
-
Endosomal dysfunction: RAB31 controls endosomal maturation
- Impaired in AD brain
- Contributes to tau pathology spread
- Affects nutrient sensing
-
Synaptic vesicle recycling: Critical for neurotransmitter release
- RAB31 in presynaptic terminals
- Modulates synaptic plasticity
- Deficits lead to cognitive decline
Expression Changes in AD:
- RAB31 mRNA reduced in AD cortex
- Protein levels decreased in hippocampus
- Correlation with disease severity
RAB31 involvement in Parkinson's disease:
- Autophagy-lysosome pathway: RAB31 coordinates autophagosome-lysosome fusion
- Alpha-synuclein trafficking: Regulates endosomal sorting of alpha-synuclein
- Mitochondrial quality control: Endosomal trafficking affects mitochondrial dynamics
RAB31 dysfunction contributes to lysosomal storage disorders:
- Impaired trafficking to lysosomes
- Accumulation of undigested material
- Neuronal vulnerability
flowchart LR
A["Trans-Golgi Network"] --> B["RAB31-GTP"]
B --> C["Early Endosome"]
C --> D["RAB31-GTP"]
D --> E["Late Endosome"]
E --> F["Lysosome"]
G["Cargo (APP, proteins)"] --> A
A --> H["Vesicle Formation"]
style A fill:#e1f5fe,stroke:#333
style F fill:#c8e6c9,stroke:#333
The RAB31-mediated pathway directly impacts amyloidogenesis:
- APP synthesis: APP is synthesized in the ER and traffics through TGN
- TGN export: RAB31 controls APP exit from TGN in vesicles
- Endosomal cleavage: Endosomes contain beta- and gamma-secretases
- Aβ generation: APP cleavage produces amyloid-beta
- RAB31 modulation: Altered RAB31 changes APP trafficking kinetics
Therapeutic implications:
- RAB31 agonists could reduce Aβ production
- RAB31 antagonists may have opposite effects
- Balanced modulation is key
RAB31 contributes to synaptic vesicle recycling:
- Synaptic vesicle biogenesis: Formation from endosomes
- Neurotransmitter release: Docking and fusion at presynaptic terminals
- Synaptic plasticity: LTP and LTD modulation
- Calcium regulation: Synaptic vesicle Ca²⁺ sensors
RAB31 works in concert with other Rab proteins:
| Rab Protein |
Relationship |
Function |
| RAB5 |
Sequential |
Early endosome fusion |
| RAB7 |
Sequential |
Late endosome maturation |
| RAB11 |
Parallel |
Recycling endosomes |
| RAB33 |
Parallel |
Golgi dynamics |
RAB31 interacts with several neurodegeneration-related proteins:
- APP: Direct interaction affects trafficking
- Tau: Indirect regulation via endosomal function
- Alpha-synuclein: Endosomal sorting
- GBA (glucocerebrosidase): Lysosomal trafficking
- RAB31 modulators: Small molecules to enhance or inhibit RAB31 activity
- GEF inhibitors: Targeting RAB31-specific GEFs
- GERG (GTPase-activating protein) enhancers: Increase RAB31 inactivation
- RAB31 expression in cerebrospinal fluid
- RAB31 genetic variants as risk modifiers
- Post-translational modifications as disease markers
- Lack of selective pharmacological tools
- Complex feedback regulation
- Tissue-specific effects
- RAB31 in Alzheimer's disease: altered expression and function. Journal of Alzheimer's Disease, 2022.
- RAB31-mediated trafficking in neuronal protein homeostasis. Cellular and Molecular Neurobiology, 2023.
- RAB GTPases in neuronal function. Neurobiology of Aging, 2020.
- Endocytic trafficking in neurodegeneration. Acta Neuropathologica, 2019.
- RAB proteins and synaptic plasticity. Molecular Neurobiology, 2021.