1r8q
From Proteopedia
FULL-LENGTH ARF1-GDP-MG IN COMPLEX WITH BREFELDIN A AND A SEC7 DOMAIN
Structural highlights
Function[ARF1_BOVIN] GTP-binding protein that functions as an allosteric activator of the cholera toxin catalytic subunit, an ADP-ribosyltransferase. Involved in protein trafficking among different compartments. Modulates vesicle budding and uncoating within the Golgi complex. Deactivation induces the redistribution of the entire Golgi complex to the endoplasmic reticulum, suggesting a crucial role in protein trafficking. In its GTP-bound form, its triggers the association with coat proteins with the Golgi membrane. The hydrolysis of ARF1-bound GTP, which is mediated by ARFGAPs proteins, is required for dissociation of coat proteins from Golgi membranes and vesicles. [CYH2_HUMAN] Acts as a guanine-nucleotide exchange factor (GEF). Promotes guanine-nucleotide exchange on ARF1, ARF3 and ARF6. Promotes the activation of ARF factors through replacement of GDP with GTP. The cell membrane form, in association with ARL4 proteins, recruits ARF6 to the plasma membrane.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedSmall GTP-binding (G) proteins are activated by GDP/GTP nucleotide exchange stimulated by guanine nucleotide exchange factors (GEFs). Nucleotide dissociation from small G protein-GEF complexes involves transient GDP-bound intermediates whose structures have never been described. In the case of Arf proteins, small G proteins that regulate membrane traffic in eukaryotic cells, such intermediates can be trapped either by the natural inhibitor brefeldin A or by charge reversal at the catalytic glutamate of the Sec7 domain of their GEFs. Here we report the crystal structures of these intermediates that show that membrane recruitment of Arf and nucleotide dissociation are separate reactions stimulated by Sec7. The reactions proceed through sequential rotations of the Arf.GDP core towards the Sec7 catalytic site, and are blocked by interfacial binding of brefeldin A and unproductive stabilization of GDP by charge reversal. The structural characteristics of the reaction and its modes of inhibition reveal unexplored ways in which to inhibit the activation of small G proteins. Structural snapshots of the mechanism and inhibition of a guanine nucleotide exchange factor.,Renault L, Guibert B, Cherfils J Nature. 2003 Dec 4;426(6966):525-30. PMID:14654833[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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