4o8q
From Proteopedia
Crystal structure of bovine MHD domain of the COPI delta subunit at 2.15 A resolution
Structural highlights
Function[COPD_BOVIN] 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). Publication Abstract from PubMedThe heptameric COPI coat (coatomer) plays an essential role in vesicular transport in the early secretory system of eukaryotic cells. While the structures of some of the subunits have been determined, that of the delta-COP subunit has not been reported to date. The delta-COP subunit is part of a subcomplex with structural similarity to tetrameric clathrin adaptors (APs), where delta-COP is the structural homologue of the AP mu subunit. Here, the crystal structure of the mu homology domain (MHD) of delta-COP (delta-MHD) obtained by phasing using a combined SAD-MR method is presented at 2.15 A resolution. The crystallographic asymmetric unit contains two monomers that exhibit short sections of disorder, which may allude to flexible regions of the protein. The delta-MHD is composed of two subdomains connected by unstructured linkers. Comparison between this structure and those of known MHD domains from the APs shows significant differences in the positions of specific loops and beta-sheets, as well as a more general change in the relative positions of the protein subdomains. The identified difference may be the major source of cargo-binding specificity. Finally, the crystal structure is used to analyze the potential effect of the I422T mutation in delta-COP previously reported to cause a neurodegenerative phenotype in mice. Structure of the bovine COPI delta subunit mu homology domain at 2.15 A resolution.,Lahav A, Rozenberg H, Parnis A, Cassel D, Adir N Acta Crystallogr D Biol Crystallogr. 2015 Jun;71(Pt 6):1328-34. doi:, 10.1107/S1399004715006203. Epub 2015 May 14. PMID:26057672[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Adir, N | Cassel, D | Lahav, A | Rozenberg, H | Mhd | Protein transport
