In resting (unstimulated) cells, glycogen synthase kinase 3 (GSK3) phosphorylates and inactivates glycogen synthase (GS), as shown in the diagram below. Reactivation of GS is catalysed by protein phosphatases, but these are less active than GSK3, so very little GS is present in the active form. [Scroll down.]
|1||PKB is activated as described for glucose transport.|
|2||Activated PKB phosphorylates and inactivates GSK3.|
|3||Phosphatases reactivate glycogen synthase after the inhibitory pathways are disabled.|
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|GSK3||glycogen synthase kinase 3|
|PKB||protein kinase B|
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