RAB18, member RAS oncogene family
The RAB18 gene provides instructions for producing the RAB18 protein, which functions as a GTPase. Often referred to as molecular switches, GTPases can be turned on and off. They are turned on (active) when they are attached (bound) to a molecule called GTP and are turned off (inactive) when they are bound to another molecule called GDP. When active, RAB18 is involved in a process called vesicle trafficking, which moves proteins and other molecules within cells in sac-like structures called vesicles. RAB18 regulates the movement of substances between compartments in cells and the storage and release of fats (lipids) by structures called lipid droplets. The protein also appears to play a role in a process called autophagy, which helps clear unneeded materials from cells. RAB18 is important for the organization of a cell structure called the endoplasmic reticulum, which is involved in protein processing and transport.
At least five mutations in the RAB18 gene have been found to cause Warburg micro syndrome, which is the most severe of the disorders caused by RAB18 deficiency. Warburg micro syndrome is characterized by multiple eye abnormalities, vision impairment, severe intellectual disability, and a reduction of the hormones that direct sexual development (hypogonadotropic hypogonadism).
The RAB18 gene mutations that cause Warburg micro syndrome eliminate the function of the RAB18 protein. It is unclear how a shortage (deficiency) of RAB18 activity leads to eye problems, brain abnormalities, and other features of Warburg micro syndrome.
- RAB18 small GTPase
- ras-related protein Rab-18 isoform 1
- ras-related protein Rab-18 isoform 2
- ras-related protein Rab-18 isoform 3
- ras-related protein Rab-18 isoform 4
- ras-related protein Rab-18 isoform 5