Fab1p and AP1 are required for trafficking of endogenously ubiquitylated cargoes to the vacuole lumen in S. cerevisiae

Phelan, John P., Millson, Stefan H., Parker, Peter J., Piper, Peter W. and Cooke, Frank T. (2006) Fab1p and AP1 are required for trafficking of endogenously ubiquitylated cargoes to the vacuole lumen in S. cerevisiae. Journal of Cell Science, 119 . pp. 4225-4234. ISSN 0021-9533

Full content URL: http://dx.doi.org/10.1242/jcs.03188

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In S. cerevisiae synthesis of phosphatidylinositol (3,5)-bisphosphate [PtdIns(3,5)P2] by Fab1p is required for several cellular events, including an as yet undefined step in the ubiquitin-dependent trafficking of some integral membrane proteins from the trans-Golgi network to the vacuole lumen. AP-1 is a heterotetrameric clathrin adaptor protein complex that binds cargo proteins and clathrin coats, and regulates bi-directional protein trafficking between the trans-Golgi network and the endocytic/secretory pathway. Like fab1Δ cells, AP-1 complex component mutants have lost the ability to traffic ubiquitylated cargoes to the vacuole lumen – the first demonstration that AP-1 is required for this process. Deletion mutants of AP-1 complex components are compromised in their ability to synthesize PtdIns(3,5)P2, indicating that AP-1 is required for correct in vivo activation of Fab1p. Furthermore, wild-type protein sorting can be restored in AP-1 mutants by overexpression of Fab1p, implying that the protein-sorting defect in these cells is as a result of disruption of PtdIns(3,5)P2 synthesis. Finally, we show that Fab1p and Vac14p, an activator of Fab1p, are also required for another AP-1-dependent process: chitin-ring deposition in chs6Δ cells. Our data imply that AP-1 is required for some Fab1p and PtdIns(3,5)P2-dependent processes.

Additional Information:Advance Online Article September 26, 2006
Keywords:AP-1, Clathrin, Fab1p, MVB trafficking
Subjects:C Biological Sciences > C700 Molecular Biology, Biophysics and Biochemistry
C Biological Sciences > C500 Microbiology
Divisions:College of Science > School of Life Sciences
ID Code:15328
Deposited On:07 Oct 2014 17:27

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