4c0a

Arf1(Delta1-17)in complex with BRAG2 Sec7-PH domain

spinqualitylabelsall models 4c0a, resolution 3.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4c0a is a 8 chain structure with sequence from Bos taurus and Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3.3Å Ligands: G3D Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function IQEC1_HUMAN In addition to accelerate GTP gamma S binding by ARFs of all three classes, it appears to function preferentially as a guanine nucleotide exchange protein for ARF6, mediating internalisation of beta-1 integrin. Publication Abstract from PubMed The mechanisms whereby guanine nucleotide exchange factors (GEFs) coordinate their subcellular targeting to their activation of small GTPases remain poorly understood. Here we analyzed how membranes control the efficiency of human BRAG2, an ArfGEF involved in receptor endocytosis, Wnt signaling, and tumor invasion. The crystal structure of an Arf1-BRAG2 complex that mimics a membrane-bound intermediate revealed an atypical PH domain that is constitutively anchored to the catalytic Sec7 domain and interacts with Arf. Combined with the quantitative analysis of BRAG2 exchange activity reconstituted on membranes, we find that this PH domain potentiates nucleotide exchange by about 2,000-fold by cumulative conformational and membrane-targeting contributions. Furthermore, it restricts BRAG2 activity to negatively charged membranes without phosphoinositide specificity, using a positively charged surface peripheral to but excluding the canonical lipid-binding pocket. This suggests a model of BRAG2 regulation along the early endosomal pathway that expands the repertoire of GEF regulatory mechanisms. Notably, it departs from the auto-inhibitory and feedback loop paradigm emerging from studies of SOS and cytohesins. It also uncovers a novel mechanism of unspecific lipid-sensing by PH domains that may allow sustained binding to maturating membranes. Integrated Conformational and Lipid-Sensing Regulation of Endosomal ArfGEF BRAG2.,Aizel K, Biou V, Navaza J, Duarte LV, Campanacci V, Cherfils J, Zeghouf M PLoS Biol. 2013 Sep;11(9):e1001652. doi: 10.1371/journal.pbio.1001652. Epub 2013 , Sep 10. PMID:24058294 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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