Endocytic downreglulation of the yeast high affinity glucose transporters Hxt2 and Hxt4
Open AccessGlucose is the preferred carbon and energy source of the budding yeast Saccharomyces cerevisiae. The yeast prefers to convert glucose to pyruvate via glycolysis even in the presence of oxygen (aerobic fermentation). Because fermentation is an inefficient way to produce energy, the yeast cells must pump a large amount of glucose through glycolysis. They do so in part by up-regulating glucose transporters. S. cerevisiae has 17 hexose transporters that have different affinities for glucose whose expression and stability are regulated by different concentrations of glucose. This enables the yeast cells to adapt to fluctuating extracellular glucose concentrations in wild environments. Previous research shows that low affinity glucose transporter Hxt1 is endocytosed and degraded in the vacuole in response to glucose depletion. In this study, I investigated whether the high affinity glucose transporters Hx2 and Hxt4 are regulated in a similar manner. My results suggest that Hxt2 and Hxt4 glucose transporters are internalized by endocytosis and targeted to the vacuole for degradation in response to high glucose. However, high glucose-induced degradation of Hxt2 and Hxt4 is prevented in cells lacking proteins involved in endocytosis, such as End3, Doa4 and Rsp5, suggesting it occurs in an ubiquitination-dependent manner. I also show that ubiquitination of Hxt4 is mediated by the Art2 and Art5 arrestin-related trafficking adaptors. Based on these observations, I conclude that stability of yeast glucose transporters may be associated with their affinities for glucose.
- All rights reserved
Notice to Authors
If you are the author of this work and you have any questions about the information on this page, please use the Contact form to get in touch with us.