Mecanismos de regulación de transportadores de iones y nutrientes a través de proteínas de tráfico relacionadas con las arrestinas
[EN] Any living cell needs to maintain adequate levels of nutrients and ions to ensure the continuity of its functions. The first step in the maintenance of both ion and nutrient homeostasis is their uptake from the extrenal environment, where plasma membrane transporter proteins play an important r...
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| Tipo de recurso: | tesis doctoral |
| Fecha de publicación: | 2016 |
| País: | España |
| Institución: | Universitat Politècnica de València (UPV) |
| Repositorio: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Idioma: | español |
| OAI Identifier: | oai:riunet.upv.es:10251/60149 |
| Acceso en línea: | https://riunet.upv.es/handle/10251/60149 |
| Access Level: | acceso abierto |
| Palabra clave: | Levadura Transporte de membrana Iones Nutrientes Arrestinas Fosforilación Ubiquitinación BIOQUIMICA Y BIOLOGIA MOLECULAR |
| Sumario: | [EN] Any living cell needs to maintain adequate levels of nutrients and ions to ensure the continuity of its functions. The first step in the maintenance of both ion and nutrient homeostasis is their uptake from the extrenal environment, where plasma membrane transporter proteins play an important role. The regulation of both the activity and abundance of permeases in the plasma membrane is a pivotal aspect of the cellular response to different environmental conditions. Therefore, deciphering the pathways that regulate the function or the presence of these transport proteins is important for a better understanding of cell physiology and stress responses. Transcriptional regulation is a contributor to the control of the abundance of plasma membrane transporters, and more specifically in the yeast model Saccharomyces cerevisiae a strong transcriptional regulation of the hexose transporters has been demonstrated. However, there are other important levels for the control and maintenance of glucose homeostasis, such as post-translational regulation of glucose transporters, which are still being defined. Ubiquitination, as a signal for endocytosis of membrane proteins, mediated by the E3 ubiquitin ligase Rsp5 has been demonstrated for many transporters, including the HXT family. In recent years, several studies have shown the involvement of the ART protein family (Arrestin-Releated Trafficking proteins) in this process, acting as adapters for Rsp5 and providing specificity to the ubiquitination of permeases in response to changes in environmental conditions. In turn, the members of this family of adapter proteins are targets of post-translational modifications, such as phosphorylation or ubiquitination, affecting their activity and adding an additional level in the regulation of transporter interactions. Previous studies have demonstrated the existence of a genetic interaction between the high affinity glucose transporter Hxt6 and the Rsp5 adapter protein, Rod1 (Art4). In turn, the Snf1 kinase was shown to be involved in the phosphorylation of this adapter protein, suggesting a possible role in the regulation of its activity. With this background, and taking into consideration the interaction of 14-3-3 proteins with other adapter proteins, in this study the biochemical characterization of the Art4-Snf1-14-3-3 signaling pathway involved in the regulation of the endocytosis of the glucose transporter Hxt6 and the effect of Snf1 and 14-3-3 proteins (Bmh2) on intracellular traffic of the Hxt6-Art4 complex will be investigated. Similarly, the effect of Art4, and its paralogue Rog3 (Art7), on Hxt6 levels and the phenotypes of other glucose transporter mutants, such as hxt1 and hxt3 will be analyzed to determine whetherthese transporters display a common regulatory mechanism also involving Art4 and Art7. In short, this thesis aims to provide new data on the post-translational regulation of the HXT transporters through the Rsp5 adapter family of ART proteins, with emphasis on biochemical aspects, such as phosphorylation, and molecular and cellular aspects, such as intracellular trafficking and permease stability |
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