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7759928 
Journal Article 
Structure of the complete, membrane-assembled COPII coat reveals a complex interaction network 
Hutchings, J; Stancheva, VG; Brown, NR; Cheung, ACM; Miller, EA; Zanetti, G 
2021 
1 
Nature Communications
EISSN: 2041-1723 
12 
1 
2034-2034 
English 
33795673 
COPII mediates Endoplasmic Reticulum to Golgi trafficking of thousands of cargoes. Five essential proteins assemble into a two-layer architecture, with the inner layer thought to regulate coat assembly and cargo recruitment, and the outer coat forming cages assumed to scaffold membrane curvature. Here we visualise the complete, membrane-assembled COPII coat by cryo-electron tomography and subtomogram averaging, revealing the full network of interactions within and between coat layers. We demonstrate the physiological importance of these interactions using genetic and biochemical approaches. Mutagenesis reveals that the inner coat alone can provide membrane remodelling function, with organisational input from the outer coat. These functional roles for the inner and outer coats significantly move away from the current paradigm, which posits membrane curvature derives primarily from the outer coat. We suggest these interactions collectively contribute to coat organisation and membrane curvature, providing a structural framework to understand regulatory mechanisms of COPII trafficking and secretion. 
Animals; COP-Coated Vesicles chemistry; COP-Coated Vesicles metabolism; COP-Coated Vesicles ultrastructure; Cryoelectron Microscopy; Electron Microscope Tomography; Endoplasmic Reticulum metabolism; Endoplasmic Reticulum ultrastructure; Golgi Apparatus metabolism; Golgi Apparatus ultrastructure; Humans; Models; Molecular; Protein Binding; Protein Conformation; Protein Interaction Maps; Protein Transport; Saccharomyces cerevisiae genetics; Saccharomyces cerevisiae metabolism; Sf9 Cells; Spodoptera; Vesicular Transport Proteins metabolism; Index Medicus