| Autor: |
Pinson, Benoît, Napias, Christian, Chevallier, Jean, Van den Broek, Peter J.A., Brèthes, Daniel |
| Zdroj: |
Journal of Biological Chemistry; November 1997, Vol. 272 Issue: 46 p28918-28924, 7p |
| Abstrakt: |
The purine-cytosine permease is a carrier localized in the plasma membrane of the yeast Saccharomyces cerevisiae.The energetics of cytosine transport catalyzed by this permease has been studied in an artificial system obtained by fusion between proteoliposomes containing beef heart cytochromecoxidase and plasma membrane-enriched fractions of aS. cerevisiaestrain overexpressing the permease. Upon addition of an energy donor, a proton-motive force (inside alkaline and negative) is created in this system and promotes cytosine accumulation. By using different phospholipids, it is shown that cytosine uptake is dependent on the phospholipids surrounding the carrier. It was demonstrated that the purine-cytosine permease is able to catalyze a secondary active transport of cytosine. By using nigericin and valinomycin, the ΔpH component of the proton-motive force is shown to be the only force driving nucleobase accumulation. Moreover, transport measurements done at two pH values have shown that alkalinization of intravesicular pH leads to a significant increase in cytosine uptake rate. Finally, no specific role of K+ions on cytosine transport could be demonstrated in this system. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
