[Correlation of active and inactive forms of phosphorylase and glycogen synthetase in the liver of the developing chick embryo]

The marked changes in the activity and ratio of the active and inactive forms of glycogen synthetase and phosphorylase were found in the liver of developing chick embryo. The activity of phosphorylase increased in the liver from the 8th day of incubation till the end of embryogenesis. The practically complete activation of the inactive form of this enzyme was noted in the end of embryogenesis. The activity of glycogen synthetase in the liver increased till the 17th day of incubation and sharply decreased more than 6 times thereafter. The maximum of the active form of glycogen synthetase (1/3 of total activity) was noted on the 17th day as well. The changes in the content of glycogen synthetase in the liver are synchronized with those in the activity and ratio of the active and inactive forms of glycogen synthetase. The role of changes in the concentration of glucose and glucose-6-phosphate in the control of ratio of the active and inactive forms of enzymes of glycogen metabolism is discussed.