Sit4p/PP6 regulates ER-to-Golgi traffic by controlling the dephosphorylation of COPII coat subunits
| Autor: | Kevin Thorsen, Jinzhong Zhang, Susan Ferro-Novick, Kevin D. Corbett, Jared R. Helm, Deepali Bhandari, Christopher L. Lord, Shekar Menon, Shuliang Chen, Jesse C. Hay |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: |
Saccharomyces cerevisiae Proteins
Protein subunit Vesicular Transport Proteins Golgi Apparatus macromolecular substances Saccharomyces cerevisiae Biology Endoplasmic Reticulum 03 medical and health sciences symbols.namesake 0302 clinical medicine Chlorocebus aethiops Animals Humans Protein Phosphatase 2 Phosphorylation Molecular Biology COPII 030304 developmental biology 0303 health sciences Endoplasmic reticulum Vesicle Membrane Proteins Cell Biology COPI Articles COP-Coated Vesicles Golgi apparatus Cell biology Membrane Trafficking COS Cells symbols 030217 neurology & neurosurgery HeLa Cells |
| Zdroj: | Molecular Biology of the Cell |
| ISSN: | 1939-4586 1059-1524 |
| Popis: | Previous studies show that the COPII coat is phosphorylated. The phosphorylated coat, however, cannot rebind to the ER to initiate a new round of vesicle budding. The present study shows that Sit4p/PP6, a Ser/Thr phosphatase, dephosphorylates the COPII coat. Consistent with a role in coat recycling, Sit4p/PP6 regulates ER-to-Golgi traffic. Traffic from the endoplasmic reticulum (ER) to the Golgi complex is initiated when the activated form of the GTPase Sar1p recruits the Sec23p-Sec24p complex to ER membranes. The Sec23p-Sec24p complex, which forms the inner shell of the COPII coat, sorts cargo into ER-derived vesicles. The coat inner shell recruits the Sec13p-Sec31p complex, leading to coat polymerization and vesicle budding. Recent studies revealed that the Sec23p subunit sequentially interacts with three different binding partners to direct a COPII vesicle to the Golgi. One of these binding partners is the serine/threonine kinase Hrr25p. Hrr25p phosphorylates the COPII coat, driving the membrane-bound pool into the cytosol. The phosphorylated coat cannot rebind to the ER to initiate a new round of vesicle budding unless it is dephosphorylated. Here we screen all known protein phosphatases in yeast to identify one whose loss of function alters the cellular distribution of COPII coat subunits. This screen identifies the PP2A-like phosphatase Sit4p as a regulator of COPII coat dephosphorylation. Hyperphosphorylated coat subunits accumulate in the sit4Δ mutant in vivo. In vitro, Sit4p dephosphorylates COPII coat subunits. Consistent with a role in coat recycling, Sit4p and its mammalian orthologue, PP6, regulate traffic from the ER to the Golgi complex. |
| Databáze: | OpenAIRE |
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