title: ER arrival sites for COPI vesicles localize to hotspots of membrane trafficking.
abstract: COPI-coated vesicles mediate retrograde membrane traffic from the cis-Golgi to the endoplasmic reticulum (ER) in all eukaryotic cells. However, it is still unknown whether COPI vesicles fuse everywhere or at specific sites with the ER membrane. Taking advantage of the circumstance that the vesicles still carry their coat when they arrive at the ER, we have visualized active ER arrival sites (ERAS) by monitoring contact between COPI coat components and the ER-resident Dsl tethering complex using bimolecular fluorescence complementation (BiFC). ERAS form punctate structures near Golgi compartments, clearly distinct from ER exit sites. Furthermore, ERAS are highly polarized in an actin and myosin V-dependent manner and are localized near hotspots of plasma membrane expansion. Genetic experiments suggest that the COPI•Dsl BiFC complexes recapitulate the physiological interaction between COPI and the Dsl complex and that COPI vesicles are mistargeted in dsl1 mutants. We conclude that the Dsl complex functions in confining COPI vesicle fusion sites.
authors.affiliation: Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
authors.forename: Saskia
authors.initials: S
authors.lastname: Schröter
authors.affiliation: Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Beckmann
authors.affiliation: Department of Neurobiology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany hschmit@mpibpc.mpg.de.
authors.forename: Hans Dieter
authors.identifier: 0000-0001-6152-2716
authors.initials: HD
authors.lastname: Schmitt
mesh_terms: D022181:COP-Coated Vesicles / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D008561:Membrane Fusion; D008856:Microscopy, Fluorescence; D012441:Saccharomyces cerevisiae / Q000378:metabolism
keywords: BiFC; COPI vesicles; Dsl1 complex; Golgi‐ER retrograde transport; vesicle tethering