5kyu
From Proteopedia
crystal structure of Sec23 and TANGO1 peptide2 complex
Structural highlights
Disease[SC23A_HUMAN] Defects in SEC23A are the cause of craniolenticulosutural dysplasia (CLSD) [MIM:607812]; also known as cranio-lenticulo-sutural dysplasia. CLSD is an autosomal recessive syndrome characterized by late-closing fontanels, sutural cataracts, facial dysmorphisms and skeletal defects.[1] Function[SC23A_HUMAN] Component of the COPII coat, that covers ER-derived vesicles involved in transport from the endoplasmic reticulum to the Golgi apparatus. COPII acts in the cytoplasm to promote the transport of secretory, plasma membrane, and vacuolar proteins from the endoplasmic reticulum to the Golgi complex. [SC24D_HUMAN] Component of the COPII coat, that covers ER-derived vesicles involved in transport from the endoplasmic reticulum to the Golgi apparatus. COPII acts in the cytoplasm to promote the transport of secretory, plasma membrane, and vacuolar proteins from the endoplasmic reticulum to the Golgi complex. Publication Abstract from PubMedThe supramolecular cargo procollagen is loaded into coat protein complex II (COPII)-coated carriers at endoplasmic reticulum (ER) exit sites by the receptor molecule TANGO1/cTAGE5. Electron microscopy studies have identified a tubular carrier of suitable dimensions that is molded by a distinctive helical array of the COPII inner coat protein Sec23/24*Sar1; the helical arrangement is absent from canonical COPII-coated small vesicles. In this study, we combined X-ray crystallographic and biochemical analysis to characterize the association of TANGO1/cTAGE5 with COPII proteins. The affinity for Sec23 is concentrated in the proline-rich domains (PRDs) of TANGO1 and cTAGE5, but Sec23 recognizes merely a PPP motif. The PRDs contain repeated PPP motifs separated by proline-rich linkers, so a single TANGO1/cTAGE5 receptor can bind multiple copies of coat protein in a close-packed array. We propose that TANGO1/cTAGE5 promotes the accretion of inner coat proteins to the helical lattice. Furthermore, we show that PPP motifs in the outer coat protein Sec31 also bind to Sec23, suggesting that stepwise COPII coat assembly will ultimately displace TANGO1/cTAGE5 and compartmentalize its operation to the base of the growing COPII tubule. TANGO1/cTAGE5 receptor as a polyvalent template for assembly of large COPII coats.,Ma W, Goldberg J Proc Natl Acad Sci U S A. 2016 Sep 6;113(36):10061-6. doi:, 10.1073/pnas.1605916113. Epub 2016 Aug 22. PMID:27551091[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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