Dokument: Analysis of protein trafficking in the yeast Saccharomyces cerevisiae
| Titel: | Analysis of protein trafficking in the yeast Saccharomyces cerevisiae | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=3220 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20051010-001220-2 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Krsmanovic, Tamara [Autor] | |||||||
| Dateien: |
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| Beitragende: | Prof. Dr. Kölling-Paternoga, Ralf [Gutachter] Prof. Dr. Knust, Elisabeth [Gutachter] | |||||||
| Stichwörter: | heat-shock, stress response, protein turnover, cell polarity, recycling, protein ubiquitination, E3 ligase, STE6 trafficking | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 570 Biowissenschaften; Biologie | |||||||
| Beschreibung: | The yeast ABC-transporter Ste6 is rapidly internalized from the cell surface and transported to the vacuole. Trafficking to the vacuole is regulated by ubiquitination. However, the ubiquitin machinery involved is still unknown. Rsp5 is a HECT E3 ubiquitin ligase implicated in ubiquitination of many membrane proteins. Therefore the role of Rsp5 in Ste6 trafficking and ubiquitination was examined. We found that Ste6 trafficking was indeed affected in the rsp5-1 mutant. The Ste6 protein was no longer delivered to the vacuole, but instead accumulated at the vacuolar membrane. However, Rsp5 was not the E3 ligase for the Ste6 protein, since Ste6 ubiquitination was not affected in the rsp5-1 mutant, suggesting that the observed effects are indirect. Indeed, we found that free ubiquitin levels were reduced in this mutant, indicating that this could be the problem in the rsp5-1 mutant. It appears that reduced synthesis of ubiquitin contributes to ubiquitin depletion. A transient inhibition of protein synthesis is observed in wildtype upon heat-shock. And, while wildtype cells recover quickly from this transient arrest, the rsp5-1 cells remain arrested, suggesting that Rsp5 is important for recovery from heat-induced protein synthesis arrest. In addition, the role of ubiquitination on Ste6 trafficking was studied. The distribution of Ste6 variants with reduced ubiquitination was examined. We found evidence that ubiquitination controls Ste6 sorting in the early endocytic pathway. While wildtype Ste6 was mainly localized to internal structures, ubiquitination deficient Ste6 variants accumulated at the cell surface in a polar fashion. However, in a recycling deficient ypt6-2 mutant, these Ste6 variants were trapped inside the cell, indicating that their polar localization is achieved through endocytic recycling and localized exocytosis ("kinetic polarization"). Furthermore, it appears that Ste6 cycles through early endosomes, since its recycling was partially affected in the sorting nexin mutant snx4?. The identification of putative recycling signals in Ste6 suggests that recycling is a signal mediated process. Endocytic recycling and localized exocytosis could be important for Ste6 polarization during the mating process. | |||||||
| Lizenz: |  Urheberrechtsschutz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Biologie | |||||||
| Dokument erstellt am: | 10.10.2005 | |||||||
| Dateien geändert am: | 12.02.2007 | |||||||
| Promotionsantrag am: | 28.01.2005 | |||||||
| Datum der Promotion: | 28.01.2005 |
