ADP ribosylation factor
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ADP Ribosylation Factors (ARFs) are members of the ARF family of GTP-binding proteins of the Ras superfamily.
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[edit] Phylogeny
There are currently 6 known mammalian ARF proteins, which are divided into three classes of ARFs:
[edit] Structure
ARFs are small proteins of approximately 20 kD in size. They contain two switch regions, which change relative positions between cycles of GDP/GTP-binding. ARFs are frequently myristoylated in their N-terminal region, which contributes to their membrane association.
[edit] Function
ARFs are GTP-binding proteins with intrinsic GTP hydrolysis activity (GTPases). Like other small GTPases, ARFs are thought to be activated when they are GTP-bound, and deactivated upon GTP hydrolysis to GDP. ARFs frequently are involved in the regulation of membrane traffic and budding of donor membranes. ARF activation is regulated by GDP exchange factors (GEFs) and GTPase activating proteins (GAPs), which bidirectionally regulate the GDP/GTP state of the ARF protein. ARFs are soluble, but myristoylated so they are often found associated with membranes.
[edit] References
- Donaldson JG, Honda A. "Localization and function of Arf family GTPases," Biochem Soc Trans. 2005 Aug;33(Pt 4):639-42. NCBI Pubmed
Heterotrimeric G protein: Transducin
Small GTPase: Ras - Rab (Rab27) - Arf (Arf6) - Ran - Rheb - Rhoa
Elongation factor (Prokaryotic, Eukaryotic)
Dynamin (is a GTPase, is not a G protein)
