Two Forms of Yeast Glycogen Synthetase and Their Role in Glycogen Accumulation
- 1 July 1970
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 66 (3), 967-974
- https://doi.org/10.1073/pnas.66.3.967
Abstract
The glycogen content of yeast rises dramatically just before the onset of the stationary phase of growth. Concomitantly, a rapid increase was found in the glucose 6-phosphate-independent (I) activity of glycogen synthetase, as well as in the total amount of enzyme. A mutant (GS 1-36) was obtained, which did not accumulate glycogen during growth. The synthetase from this strain was in the glucose 6-phosphate-dependent (D) form at all times. The total enzymatic activity of the mutant also increased sharply at the end of the logarithmic phase, although its maximal value was only one third that of the parent strain. Incubation with glucose of wild type resting cells from the logarithmic phase resulted in a slow accumulation of glycogen, which was accelerated after 20 min. At the same time a transformation from the D to I form of the enzyme was detected. The same slow initial rate of glycogen deposition was found with stationary cells of mutant GS 1-36, but the rate gradually declined to zero, rather than accelerating. The interconversion of the I and D forms was obtained with extracts from cells harvested during different phases of growth. Examination of the properties of the I and D forms showed that the latter was much more strongly inhibited by ATP at low glucose 6-phosphate concentration. These findings clearly establish the fundamental role of the I form in glycogen accumulation. When taken together with previous results, they also show that the physiological significance of the I-D interconversion depends on the concentration of glucose 6-phosphate. Under certain conditions glucsoe 6-phosphate appears to regulate directly the activity of the predominant form of the enzyme.Keywords
This publication has 12 references indexed in Scilit:
- Possibility of metabolite control of liver glycogen synthetase activityBiochemistry, 1970
- Regulation of glycogen synthesis in the intact yeast cellBiochemistry, 1969
- The Influence of Inorganic Phosphate, Adenosine Triphosphate and Glucose 6‐Phosphate on the Activity of Liver Glycogen SynthetaseEuropean Journal of Biochemistry, 1968
- Regulation of muscle glycogen synthetase by metabolites. Differential effects on the I and D formsBiochemistry, 1968
- Allosteric Properties of Yeast Glycogen Synthetase. I. General Kinetic Study*Biochemistry, 1967
- Spontaneous Mutants of Yeast Deficient in GlycogenNature, 1967
- Measurement of Low Energy Beta-Emitters in Aqueous Solution by Liquid Scintillation Counting of Emulsions.Analytical Chemistry, 1965
- FACTORS AFFECTING ACTIVITY OF MUSCLE GLYCOGEN SYNTHETASE .2. REGULATION BY CA++1965