[^1]
| Symbol |
RAB18 |
| Full Name |
RAB18, Member RAS Oncogene Family |
| Chromosome |
20p12.1 |
| NCBI Gene |
22931 |
| Ensembl |
ENSG00000099250 |
| OMIM |
602207 |
| UniProt |
Q9U32 |
| Diseases |
[Warburg Micro Syndrome](/diseases/warburg-micro-syndrome), [Parkinson's Disease](/diseases/parkinsons-disease), [Alzheimer's Disease](/diseases/alzheimers) |
| Expression |
Ubiquitously expressed; high expression in brain, retina, endocrine tissues |
RAB18 is a member of the RAB GTPase family located on chromosome 20p12.1. RAB18 is a small GTP-binding protein involved in membrane trafficking, particularly at the endoplasmic reticulum (ER) and Golgi apparatus. RAB18 plays critical roles in cellular processes including protein secretion, lipid transport, and neuronal function. Mutations in RAB18 cause Warburg Micro syndrome, a severe developmental disorder, and the gene has been implicated in neurodegenerative diseases [1][2].
The RAB18 gene spans approximately 12 kb and consists of 6 exons. The gene encodes a 206-amino acid small GTPase protein.
- Chromosome: 20p12.1
- Location: chr20: 13493931-13506731
- Strand: Minus strand
- Exons: 6
¶ Protein Structure and Function
¶ Domain Architecture
RAB18 contains:
- GTP-binding domain: Responsible for nucleotide binding and hydrolysis
- Switch regions: Conformational changes between active/inactive states
- Hypervariable C-terminal region: Membrane targeting and effector interactions
- CAAX motif: Prenylation for membrane association
RAB18 cycles between active (GTP-bound) and inactive (GDP-bound) states:
- GTP-bound state: Active, interacts with effector proteins
- GAPs (GTPase-activating proteins): Accelerate GTP hydrolysis
- GEFs (Guanine nucleotide exchange factors): Promote GDP release and GTP loading
- GDIs (GDP dissociation inhibitors): Extract RAB18 from membranes
- ER-Golgi transport: Regulates protein trafficking between ER and Golgi
- Lipid droplet metabolism: Associates with lipid droplets
- Endosomal trafficking: Involved in endocytic pathway
- Synaptic vesicle trafficking: Essential for neurotransmitter release
- Axonal transport: Mediates vesicular transport in neurons
- Dendritic spine morphology: Regulates spine development
RAB18 mutations cause Warburg Micro syndrome:
- Severe developmental brain malformations
- Microcephaly
- Hypogonadotropic hypogonadism
- Intellectual disability
- Ocular abnormalities
- Agenesis of the corpus callosum
Pathogenic variants:
- Missense mutations (loss-of-function)
- Truncating mutations
- Splice-site mutations
RAB18 dysfunction is implicated in:
-
Parkinson's disease:
- Altered RAB18 levels in PD brain
- Involvement in alpha-synuclein trafficking
- Mitochondrial quality control
-
Alzheimer's disease:
- APP trafficking alterations
- Synaptic vesicle dysfunction
- Endoplasmic reticulum stress
-
Other conditions:
- Hereditary spastic paraplegia
- Neurodevelopmental disorders
RAB18 is ubiquitously expressed with highest levels in:
- Brain (cerebral cortex, hippocampus)
- Retina
- Endocrine tissues (pituitary, adrenal)
- Testis
- Endoplasmic reticulum membrane
- Golgi apparatus
- Lipid droplets
- Cytoplasmic vesicles
RAB18 expression is regulated by:
- Cellular stress
- Nutrient status
- Hormonal signals
- Gene therapy: Restoring functional RAB18 in WARBS
- Small molecule modulators: Targeting RAB18 GTPase activity
- Symptomatic treatment: Management of neurological symptoms
- Understanding RAB18's role in neuronal function
- Developing therapies for WARBS
- Exploring RAB18 in neurodegenerative disease
- RAB18 mutations cause Warburg Micro syndrome. Nature Genetics, 2010.
- RAB18 and neuronal membrane trafficking. Neuroscience, 2020.
- RAB18 in Alzheimer's disease pathogenesis. Alzheimer's & Dementia, 2021.