Glycogen synthase phosphorylation

Soderling, T. R., Jett, M. F., Hutson, N. J., and Khatra, B. S., 1977, Regulation of glycogen synthase. Phosphorylation specificities of cAMP-dependent and cAMP-independent kinases for skeletal muscle synthase, /. Biol. Chem. 252 7517. 

Srivastava, A. K., Waisman, D. M., Brostrom, C. O., and Soderling, T. R., 1979, Stimulation of glycogen synthase phosphorylation by calcium-dependent regulator protein, /. Biol Chem. 254 583. 

Glycogen synthase also exists in two distinct forms which can be interconverted by the action of specific enzymes active, dephosphorylated glycogen synthase I (glucose-6-P-independent) and less active phosphorylated glycogen synthase D (glucose-6-P-dependent). The nature of phosphorylation is more complex with glycogen synthase. As many as nine serine residues on the enzyme appear to be subject to phosphorylation, each site s phosphorylation having some effect on enzyme activity. 

GSK3 phosphorylates glycogen synthase (GS), the key enzyme for glycogen synthesis which builds up the... 

Liver Activation of glycogen synthesis Activation of glycogen synthase (GS) Inactivation of glycogen synthase kinase 3 (GSK3) through phosphorylation by Akt... 

The principal enzymes controlling glycogen metabolism—glycogen phosphorylase and glycogen synthase— are regulated by allosteric mechanisms and covalent modifications due to reversible phosphorylation and... 

Like phosphorylase, glycogen synthase exists in either a phosphorylated or nonphosphorylated state. However, unlike phosphorylase, the active form is dephosphorylated (glycogen synthase a) and may be inactivated to... 

Another substrate of PKB is glycogen synthase kinase 3(5 (GSK3(5), whose phosphorylation causes its inactivation. As its name indicates, this protein kinase was originally discovered as a regulator... 

Morfini, G., Szebenyi, G., Elluru, R., Ratner, N. and Brady, S. T. Glycogen synthase kinase 3 phosphorylates kinesin light chains and negatively regulates kinesin-based motility. EMBO J. 23 281-293, 2002. 

In contrast to inhibitor 1, DARPP-32 and NIPP1, which regulate signal transduction, the function of inhibitor 2 appears to be different. There is evidence that inhibitor 2 associates with PP1, as the phosphatase is newly synthesized and contributes to the proper folding of the enzyme [40]. Inhibitor 2 can thus be considered a chaperone protein. The inactive PP 1-inhibitor 2 complex can then be activated upon phosphorylation of inhibitor 2 by glycogen synthase kinase-3. Whether this process is regulated in neurons in association with synaptic activity remains unknown. 

In the fed state when the insulin glucagon ratio is high, would you expect glycogen synthase, PK and PDH to be phosphorylated or de-phosphorylated Give reasons to support your answer. 

Glycogen synthase kinase-3 is itself subject to control by reversible phosphorylation. Stimulation of the liver cell by insulin, the key hormone of the postprandial state,... 

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