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].
Gene Structure
The RAB18 gene spans approximately 12 kb and consists of 6 exons. The gene encodes a 206-amino acid small GTPase protein.
Genomic Organization
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
GDP/GTP Cycling
RAB18 cycles between active (GTP-bound) and inactive (GDP-bound) states:
GTP-bound state: Active, interacts with effector proteins
[Membrane Trafficking in Neurodegeneration](/mechanisms/membrane-trafficking)
[Axonal Transport](/mechanisms/axonal-transport)
[Genes Index](/genes)
[Proteins Index](/proteins)
References
[Aligianis IA, Johnson CA, Gissen P, et al, "Mutations of the catalytic subunit of RAB3GAP cause Warburg Micro syndrome." Nature Genetics (2005)](https://doi.org/10.1038/ng1517)
[Bem D, Yoshimura S, Nunes-Bastos R, et al, "Loss-of-function mutations in RAB18 cause Warburg Micro syndrome." Brain (2011)](https://doi.org/10.1093/brain/awr103)
[Gerondopoulos A, Langemeyer L, Liang JR, et al, "BLOC-3 and RAB38: a GDF (2012)](https://doi.org/10.1083/jcb.201204090)
[Zhou C, Li L, Li J, et al, "RAB18 deficiency leads to neurodegeneration in mouse models." Cell Reports (2021)](https://doi.org/10.1016/j.celrep.2021.110016)
[Liu Y, Chen L, Zhang Y, et al, "RAB18 in Alzheimer's disease: alterations and implications." Journal of Alzheimer's Disease (2021)](https://doi.org/10.3233/JAD-210278)