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Phosphorylation of yeast hexokinases.
1Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115.
European Journal of Biochemistry
|June 20, 1990
Summary
Hexokinase 1 and hexokinase 2 in yeast are phosphoproteins, with highest modification occurring in low glucose conditions. This phosphorylation is regulated by cAMP-dependent protein kinase and correlates with glucose uptake.
Area of Science:
- Biochemistry
- Molecular Biology
- Yeast Genetics
Background:
- Hexokinases (HXKs) are crucial enzymes in glucose metabolism.
- Post-translational modifications, like phosphorylation, can regulate enzyme activity and function.
- Understanding HXK regulation is key to comprehending cellular energy management.
Purpose of the Study:
- To investigate the phosphorylation status of hexokinase 1 and hexokinase 2 in Saccharomyces cerevisiae.
- To explore the role of cAMP-dependent protein kinase in HXK phosphorylation.
- To correlate HXK phosphorylation with glucose uptake mechanisms.
Main Methods:
- In vivo 32P-labeling of Saccharomyces cerevisiae.
- Analysis of hexokinase phosphorylation under varying glucose concentrations.
- Genetic manipulation of strains affecting cAMP-dependent protein kinase activity (bcy1, tpk1w1).
Main Results:
- Hexokinase 1 and hexokinase 2 were identified as phosphoproteins in yeast.
- Phosphorylation levels were highest under low glucose conditions.
- cAMP-dependent protein kinase negatively regulates hexokinase phosphorylation.
- Phosphorylation extent correlated with high-affinity glucose uptake expression.
Conclusions:
- Hexokinase phosphorylation is a significant regulatory mechanism in yeast glucose metabolism.
- The cAMP-dependent protein kinase pathway modulates hexokinase phosphorylation.
- HXK phosphorylation is linked to the regulation of glucose transport systems.