3lvq
From Proteopedia
The crystal structure of ASAP3 in complex with Arf6 in transition state
Structural highlights
FunctionASAP3_HUMAN Promotes cell proliferation.[1] ARF6_HUMAN GTP-binding protein involved in protein trafficking; regulates endocytic recycling and cytoskeleton remodeling. May modulate vesicle budding and uncoating within the Golgi apparatus. Functions as an allosteric activator of the cholera toxin catalytic subunit, an ADP-ribosyltransferase. Involved in the regulation of dendritic spine development (By similarity). Contributes to the regulation of dendritic branching and filopodia extension.[2] [3] [4] 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 PubMedArfs are small G proteins that have a key role in vesicle trafficking and cytoskeletal remodeling. ArfGAP proteins stimulate Arf intrinsic GTP hydrolysis by a mechanism that is still unresolved. Using a fusion construct we solved the structure of the ArfGAP ASAP3 in complex with Arf6 in the transition state. This structure clarifies the ArfGAP catalytic mechanism and shows a glutamine((Arf6)) and an arginine finger((ASAP3)) as the important catalytic residues. Unexpectedly the structure shows a calcium ion, liganded by both proteins in the complex interface, stabilizing the interaction and orienting the catalytic machinery. Calcium stimulates the GAP activity of ASAPs, but not other members of the ArfGAP family. This type of regulation is unique for GAPs and any other calcium-regulated processes and hints at a crosstalk between Ca(2+) and Arf signaling. The structure of an Arf-ArfGAP complex reveals a Ca2+ regulatory mechanism.,Ismail SA, Vetter IR, Sot B, Wittinghofer A Cell. 2010 May 28;141(5):812-21. PMID:20510928[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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