Rab (G-protein)

Rab (G-protein)

File:Rab protein.png

A representation of the Rab G-protein.

The Rab (G-protein) is a member of the Ras superfamily of G-proteins. These proteins are involved in the regulation of intracellular trafficking of molecules, including the fusion of vesicles with their target compartments.

Structure

Rab proteins are small GTPases that are approximately 21-25 kDa in size. They consist of a GTP-binding domain and a C-terminal region that is involved in membrane association. The GTP-binding domain is highly conserved among all Rab proteins, while the C-terminal region is variable and determines the specific function of each Rab protein.

Function

Rab proteins function as molecular switches that alternate between an inactive GDP-bound state and an active GTP-bound state. This switch is regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs).

In the active state, Rab proteins can interact with various effector proteins to mediate different steps in vesicle trafficking, including vesicle formation, vesicle movement along actin and microtubule networks, and vesicle fusion with target membranes.

Clinical significance

Mutations in Rab proteins have been associated with various diseases, including cancer, neurodegenerative diseases, and immunodeficiency. For example, mutations in Rab27a cause Griscelli syndrome, a rare autosomal recessive disorder characterized by pigmentary dilution of the skin and hair, the presence of large clumps of pigment in hair shafts, and an accumulation of melanosomes in melanocytes.

See also

• Ras superfamily
• G-protein
• Vesicle
• Guanine nucleotide exchange factor
• GTPase-activating protein

Cell biology

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