ADP ribosylation factor

ADP ribosylation factor (ARF) is a type of protein that plays a crucial role in the regulation of protein trafficking and vesicle transport within cells. ARF is part of the Ras superfamily of small GTPases, which are involved in various cellular processes such as cell growth, differentiation, and survival.

Function

ARF proteins are primarily involved in the formation and budding of vesicles from the Golgi apparatus. They do this by recruiting coat proteins, such as COPI and clathrin, to the budding vesicle. ARF proteins also play a role in the regulation of phospholipase D and cholesterol transport.

ARF proteins are activated by guanine nucleotide exchange factors (GEFs), which facilitate the exchange of GDP for GTP. Once activated, ARF proteins can interact with their target proteins. Inactivation of ARF proteins occurs through the action of GTPase-activating proteins (GAPs), which stimulate the hydrolysis of GTP to GDP.

Structure

ARF proteins are small, with a molecular weight of approximately 20 kDa. They consist of a single polypeptide chain and lack an intrinsic membrane-binding domain. Instead, ARF proteins associate with membranes through a myristoylated N-terminal amino acid.

Clinical significance

Mutations in ARF proteins or their regulators have been implicated in a number of diseases, including cancer, neurodegenerative diseases, and congenital disorders of glycosylation. For example, overexpression of certain ARF proteins has been observed in various types of cancer, suggesting a potential role in tumorigenesis.

See also

• Ras superfamily
• Guanine nucleotide exchange factors
• GTPase-activating proteins
• Vesicle transport