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From Proteopedia
Crystal structure of human alpha/epsilon-COP of the COPI vesicular coat bound to alpha-COP STM2
Structural highlights
FunctionCOPE_HUMAN 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. The 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 with 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 PubMedCoat protein I (COPI)-coated vesicles mediate retrograde transport from the Golgi to the endoplasmic reticulum (ER), as well as transport within the Golgi. Major progress has been made in defining the structure of COPI coats, in vitro and in vivo, at resolutions as high as 9 A. Nevertheless, important questions remain unanswered, including what specific interactions stabilize COPI coats, how COPI vesicles recognize their target membranes, and how coat disassembly is coordinated with vesicle fusion and cargo delivery. Here, we use X-ray crystallography to identify a conserved site on the COPI subunit alpha-COP that binds to flexible, acidic sequences containing a single tryptophan residue. One such sequence, found within alpha-COP itself, mediates alpha-COP homo-oligomerization. Another such sequence is contained within the lasso of the ER-resident Dsl1 complex, where it helps mediate the tethering of Golgi-derived COPI vesicles at the ER membrane. Together, our findings suggest that alpha-COP homo-oligomerization plays a key role in COPI coat stability, with potential implications for the coordination of vesicle tethering, uncoating, and fusion. Roles of singleton tryptophan motifs in COPI coat stability and vesicle tethering.,Travis SM, Kokona B, Fairman R, Hughson FM Proc Natl Acad Sci U S A. 2019 Nov 11. pii: 1909697116. doi:, 10.1073/pnas.1909697116. PMID:31712447[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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