Sequential interactions with Sec23 control the direction of vesicle traffic

Christopher Lord, Deepali Bhandari, Shekar Menon, Majid Ghassemian, Deborah Nycz, Jesse Hay, Pradipta Ghosh, Susan Ferro-Novick

Research output: Contribution to journalArticlepeer-review

Abstract

How the directionality of vesicle traffic is achieved remains an important unanswered question in cell biology. The Sec23p/Sec24p coat complex sorts the fusion machinery (SNAREs) into vesicles as they bud from the endoplasmic reticulum (ER). Vesicle tethering to the Golgi begins when the tethering factor TRAPPI binds to Sec23p. Where the coat is released and how this event relates to membrane fusion is unknown. Here we use a yeast transport assay to demonstrate that an ER-derived vesicle retains its coat until it reaches the Golgi. A Golgi-associated kinase, Hrr25p (CK1Î́ orthologue), then phosphorylates the Sec23p/Sec24p complex. Coat phosphorylation and dephosphorylation are needed for vesicle fusion and budding, respectively. Additionally, we show that Sec23p interacts in a sequential manner with different binding partners, including TRAPPI and Hrr25p, to ensure the directionality of ER-Golgi traffic and prevent the back-fusion of a COPII vesicle with the ER. These events are conserved in mammalian cells.

Original languageEnglish
Pages (from-to)181-186
Number of pages6
JournalNature
Volume473
Issue number7346
DOIs
StatePublished - May 12 2011

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