Phosphorylation and membrane dissociation of the ARF exchange factor GBF1 in mitosis


Secretory protein trafficking is arrested and the Golgi apparatus fragmented when mammalian cells enter mitosis. These changes are thought to facilitate cell cycle progression and Golgi inheritance, and are brought about through the actions of mitotically active protein kinases. To better understand how the Golgi apparatus undergoes mitotic fragmentation we have sought to identify novel Golgi targets for mitotic kinases. We report here the identification of the ARF exchange factor GBF1 as a Golgi phosphoprotein. GBF1 is phosphorylated by CDK1-cyclin B in mitosis, which results in its dissociation from Golgi membranes. Consistent with a reduced level of GBF1 activity at the Golgi membrane there is a reduction in levels of membrane-associated GTP-bound ARF in mitotic cells. Despite the reduced levels of membrane bound GBF1 and ARF, COPI binding to the Golgi membrane appears unaffected in mitotic cells. Surprisingly, this pool of COPI is dependent upon GBF1 for its recruitment to the membrane, suggesting a low level of GBF1 activity persists in mitosis. We propose that the phosphorylation and membrane dissociation of GBF1 and the consequent reduction in ARF-GTP levels in mitosis are important for changes in Golgi dynamics and possibly other mitotic events mediated through effectors other than the COPI vesicle coat.

Publication DOI:
Divisions: College of Health & Life Sciences > School of Biosciences
College of Health & Life Sciences
College of Health & Life Sciences > School of Biosciences > Cellular and Molecular Biomedicine
Additional Information: Creative Commons Attribution Non-Commercial Licence. The Biochemical Journal and Portland Press
Uncontrolled Keywords: ADP-ribosylation factor,Golgi apparatus,Golgi-specific brefeldin A-resistant guanine nucleotide-exchange factor 1,mitosis,phosphorylation,Biochemistry,Cell Biology,Molecular Biology,General Medicine
Publication ISSN: 1470-8728
Last Modified: 17 Jul 2024 07:02
Date Deposited: 22 Jun 2012 12:32
Full Text Link: http://www.bioc ... 7/bj4270401.htm
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2010-05-01
Authors: Morohashi, Yuichi
Balklava, Zita (ORCID Profile 0000-0001-9039-9710)
Ball, Matthew
Hughes, Helen
Lowe, Martin



Version: Published Version

License: Creative Commons Attribution Non-commercial

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