Purified preparations of rabbit skeletal muscle glycogen synthase (specific activity 6 to 42 units/mg of protein) were found to be contaminated with calciumdependent kinase(s) which catalyzed the phosphorylation of glycogen phosphorylase b and glycogen synthase. In a series of glycogen synthase preparations there was a correlation between the phosphorylation rates of glycogen synthase and of ad...

The kinetics of the interaction of rabbit skeletal muscle phosphorylase kinase with glycogen has been studied using turbidimetric method (40 mM Hepes, pH 6.8, and 8.2; 20◦C). The binding of phosphorylase kinase with glycogen occurs only in the presence of Ca and Mg . According to the kinetic data, phosphorylase b favors the binding of phosphorylase kinase with glycogen. This conclusion is suppo...

Hepatic insulin resistance in the leptin-receptor defective Zucker fa/fa rat is associated with impaired glycogen synthesis and increased activity of phosphorylase-a. We investigated the coupling between phosphorylase-a and glycogen synthesis in hepatocytes from fa/fa rats by modulating the concentration of phosphorylase-a. Treatment of hepatocytes from fa/fa rats and Fa/? controls with a selec...

An S100 binding protein from skeletal muscle, R95 000, has been purified, identified as glycogen phosphorylase, and shown to be regulated in vitro by the S100 alpha isoform. When a soluble skeletal muscle fraction was subjected to a standard purification procedure for glycogen phosphorylase, R95 000 copurified with the 95 000 molecular weight glycogen phosphorylase protein standard on SDS-polya...

The major role of liver glycogen is to supply glucose to the circulation in order to maintain normal blood glucose levels. In the muscle and liver, the accumulation and breakdown of glycogen are regulated by the reciprocal activities of glycogen phosphorylase and glycogen synthase. Glycogen phosphorylase catalyses the key step of glycogen degradation and its activity is inhibited by glucose and...

A mechanistic cause for Mauriac syndrome, a syndrome of growth failure and delayed puberty associated with massive liver enlargement from glycogen deposition in children with poorly controlled type 1 diabetes, is unknown. We discovered a mutation in the catalytic subunit of liver glycogen phosphorylase kinase in a patient with Mauriac syndrome whose liver extended into his pelvis. Glycogen phos...

Abstract Glycogen is a natural polysaccharide with dendrimer structure, in which glucose frequently branched and polymerized. Functionalizing the numerous non-reducing ends on molecular surface of glycogen could be expected to enable its use various fields. We developed method for enzymatically synthesizing suitable form from sucrose by using phosphorylase branching enzyme, both belong α-amylas...

a deficiency of liver phosphorylase kinase, causing a lack of active glycogen phosphorylase, although total phosphorylase is normal. The intravenous injection of glucagon caused a rapid activation of cyclic AMP-dependent protein kinase in the liver, but no increase in either phosphorylase kinase or phosphorylase a activity. Although total glycogen synthase activity in the livers of affected rat...

Low activity of phosphorylase and increased concentration of glycogen were found in liver tissue from five children with asymptomatic hepatomegaly. In vitro activation of liver phosphorylase in these patients occurred at the rate of 10% or less of normal. Elimination of the defect by the addition of kinase that activates phosphorylase demonstrated the integrity of the phosphorylase enzyme and t...

We used metabolic control analysis to determine the flux control coefficient of phosphorylase on glycogen synthesis in hepatocytes by titration with a specific phosphorylase inhibitor (CP-91149) or by expression of muscle phosphorylase using recombinant adenovirus. The muscle isoform was used because it is catalytically active in the b-state. CP-91149 inactivated phosphorylase with sequential a...