BACKGROUND In both muscle and liver, glycogen concentrations are regulated by the complementary activities of Glycogen Phosphorylase (GP) and Glycogen Synthase (GS). GP catalyses the phosphorolytic degradation of Gycogen to Glucose-1-phosphate, the first step in the mobilization of glycogen energy stores, and is a major regulatory enzyme of glycogen metabolism. GS catalyses the transfer of the Glycosyl residue from Uridine Diphosphate Glucose (UDPG) to the non-reducing end of alpha-1,4-glucan. In other words, this enzyme converts excess glucose residues one by one into a polymeric chain for storage as glycogen. GS is a rate-determining enzyme for glycogen synthesis. The reaction is highly regulated by allosteric effectors such as glucose-6-phosphate, by phosphorylation reactions, and indirectly triggered by insulin.1 GS is directly regulated by GSK-3. GSK-3 inactivates GS by phosphorylating it at the C-terminal of Ser641, Ser645, Ser649. Moreover, GS is also regulated by Protein Phosphatase 1 (PP1), which activates it via Dephosphorylation.2 Insulin regulates this process by a hierarchal multisite Phosphorylation mechanism, in which the first kinase (PDK1) is activated by PI-3 kinase to activate second kinase Akt/PKB that leads to deactivation of the third kinase (GSK3) which is the one to inactivate GS.3 Finally, GS also cleaves the ester bond between the C1 position of glucose and the pyrophosphate of UDP itself. Mutations in this gene are associated with muscle Glycogen Storage disease.4 Alternatively spliced transcript variants encoding different isoforms have been found for this gene.
1. Roach, P.J.: Curr Mol Med 2:101–20, 2002
2. Saltiel, A.R.:Cell 104:517-29, 2001
3. Jope, R.S. & Johnson, G.V.W.:Trends in Biochem. Sci. 29:95-102, 2004
4. Ohro, M. et al: J. Clin. Invest. 102:507-18, 1998
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|Peptide sequence around aa. 644-648 (P-S-P-S-L), according to the protein NP_001155059.1|
Species & predicted
reactivity ( ):
Human, Mouse, Rat
Weight of protein:
Detects endogenous Glycogen Synthase proteins without cross-reactivity with other related proteins.
Store at -20°C, 4°C for frequent use. Avoid repeated freeze-thaw cycles.
*Optimal working dilutions must be determined by end user.