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| Mol. Biol. Cell Feb (2007); 18(2):697-706 | |
| Direct binding to Rsp5 mediates ubiquitin-independent sorting of Sna3 via the multivesicular body pathway- | |
| McNatt MW, McKittrick I, West M, Odorizzi G | |
| Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA- | |
| Abstract: The sorting of most integral membrane proteins into the lumenal vesicles of multivesicular bodies -MVBs- is dependent on the attachment of ubiquitin -Ub- to their cytosolic domains- However, Ub is not required for sorting of Sna3, an MVB vesicle cargo protein in yeast- We show that Sna3 circumvents Ub-mediated recognition by interacting directly with Rsp5, an E3 Ub ligase that catalyzes monoubiquitination of MVB vesicle cargoes- The PPAY motif in the C-terminal cytosolic domain of Sna3 binds the WW domains in Rsp5, and Sna3 is polyubiquitinated as a consequence of this association- However, Ub does not appear to be required for transport of Sna3 via the MVB pathway because its sorting occurs under conditions in which its ubiquitination is impaired- Consistent with Ub-independent function of the MVB pathway, we show by electron microscopy that the formation of MVB vesicles does not require Rsp5 E3 ligase activity- However, cells expressing a catalytically disabled form of Rsp5 have a greater frequency of smaller MVB vesicles compared with the relatively broad distribution of vesicles seen in MVBs of wild-type cells, suggesting that the formation of MVB vesicles is influenced by Rsp5-mediated ubiquitination- | |
| [PUBMED: 17182850] |   |
| Copyright © 2009, Tyers Lab, The Samuel Lunenfeld Research Institute, Mount Sinai Hospital, All Rights Reserved. |
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| BioGRID: A General Repository for Interaction Datasets. Chris Stark, Bobby-Joe Breitkreutz, Teresa Reguly, Lorrie Boucher, Ashton Breitkreutz, Mike Tyers. Nucleic Acids Res. Jan 1;34:D535-9. |