https://www.amjmed.com/article/0002-9343(94)90152-X/pdf

Diabetes mellitus: A disease of abnormal cellular calcium metabolism?

Publisher Summary This chapter discusses the characteristics of glycogen synthase and its control mechanisms. Glycogenic steroids in mammalian liver appear to act via insulin, as do puromycin and thyroxine in tadpole liver. Testosterone has been shown to increase weight and glycogen content of rat perineal muscle of castrate animals. The rat levator ani muscle present only in the male is a completely white muscle, which is part of the male reproductive system that is trophically dependent on androgens. The action of injected estrogen has been studied in the rat levator ani of the castrate rat. The covalent conversions act to interchange the allosteric control mechanisms of the two forms of the enzyme. In liver, insulin has both an effect to increase total phosphatase activity and to stimulate conversion of an inactive form of phosphatase to an active form. Glycogen synthase has no pyridoxal phosphate and has much more phosphate than phosphorylase.

Glycogen Synthase and Its Control

Inability of insulin to activate liver glycogen transferase D phosphatase in the diabetic pancreatectomized dog.

Regulation of glycogen metabolism in astrocytoma and neuroblastoma cells in culture.

New aspects of glycogen metabolism

Glycogen content and udpglucose-glucan glucosyl-transferase activity of normal human lymphocytes

1. In normal leucocytes, glycogen-transferase was only found in the glucose-6-phosphate dependent D-form. An increase in activity was observed within 30 min after glucose feeding, and is assumed to be mediated through the action of released insulin. A late secondary increase in activity occurred simultaneously with an increase in serum growth hormone. — 2. In most diabetic leucocytes, glycogen-transferase was found in both the I- (independent of glucose-6-phosphate) and D-form. The I+D activity was low in uncontrolled diabetes and increased in response to insulin treatment. The I-activity was low immediately upon isolation of the leucocytes, but increased during incubation of the enzyme, especially in the presence of Mg2+; indicating that diabetic leucocytes possess transferase-D phosphatase activity in contrast to normal cells. The D to I transformation of the enzyme was greatly increased by insulin treatment. — 3. K
 m
 for UDPG and K
 a
 for glucose-6-phosphate did not vary between normal and diabetic leucocytes. — 4. The D to I interconversion of the incubated enzyme from diabetic cells was found to depend on the concentration of ATP and ADP in the incubation medium. It is suggested, that the activating effect of Mg2+ on the D to I transformation is due to an activation of an endogenous ATP-ase and adenylate kinase.

/pdf/udp-glucose-glucan-glucosyl-transferase-activity-of-57ic400nbu.pdf

V. Esmann

Papers

Glycogen content and udpglucose-glucan glucosyl-transferase activity of normal human lymphocytes

UDP-glucose-glucan glucosyl-transferase activity of polymorphonuclear leukocytes from diabetic subjects

Purification of glycogen synthetase-D from human polymorphonuclear leukocytes