5nzu
From Proteopedia
The structure of the COPI coat linkage II
Structural highlights
FunctionCOPB2_MOUSE The coatomer is a cytosolic protein complex that binds to dilysine motifs and reversibly associates with Golgi non-clathrin-coated vesicles, which further mediate biosynthetic protein transport from the ER, via the Golgi up to the trans Golgi network. Coatomer complex is required for budding from Golgi membranes, and is essential for the retrograde Golgi-to-ER transport of dilysine-tagged proteins. In mammals, the coatomer can only be recruited by membranes associated to ADP-ribosylation factors (ARFs), which are small GTP-binding proteins; the complex also influences the Golgi structural integrity, as well as the processing, activity, and endocytic recycling of LDL receptors (By similarity). This coatomer complex protein, essential for Golgi budding and vesicular trafficking, is a selective binding protein (RACK) for protein kinase C, epsilon type. It binds to Golgi membranes in a GTP-dependent manner. Publication Abstract from PubMedCOPI coated vesicles mediate trafficking within the Golgi apparatus and between the Golgi and the endoplasmic reticulum. Assembly of a COPI coated vesicle is initiated by the small GTPase Arf1 that recruits the coatomer complex to the membrane, triggering polymerization and budding. The vesicle uncoats before fusion with a target membrane. Coat components are structurally conserved between COPI and clathrin/adaptor proteins. Using cryo-electron tomography and subtomogram averaging, we determined the structure of the COPI coat assembled on membranes in vitro at 9 A resolution. We also obtained a 2.57 A resolution crystal structure of betadelta-COP. By combining these structures we built a molecular model of the coat. We additionally determined the coat structure in the presence of ArfGAP proteins that regulate coat dissociation. We found that Arf1 occupies contrasting molecular environments within the coat, leading us to hypothesize that some Arf1 molecules may regulate vesicle assembly while others regulate coat disassembly. 9A structure of the COPI coat reveals that the Arf1 GTPase occupies two contrasting molecular environments.,Dodonova SO, Aderhold P, Kopp J, Ganeva I, Rohling S, Hagen WJH, Sinning I, Wieland F, Briggs JAG Elife. 2017 Jun 16;6. pii: e26691. doi: 10.7554/eLife.26691. PMID:28621666[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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