Phosphorylation and inactivation of glycogen synthase kinase 3 by protein kinase A.

Glycogen synthase kinase 3 (GSK-3) is implicated in multiple biological processes including metabolism, gene expression, cell fate determination, proliferation, and survival. GSK-3 activity is inhibited through phosphorylation of serine 21 in GSK-3 alpha and serine 9 in GSK-3 beta. These serine residues of GSK-3 have been previously identified as targets ...
of protein kinase B (PKB/Akt), a serine/threonine kinase located downstream of phosphatidylinositol 3-kinase. Here, we show that serine 21 in GSK-3 alpha and serine 9 in GSK-3 beta are also physiological substrates of cAMP-dependent protein kinase A. Protein kinase A physically associates with, phosphorylates, and inactivates both isoforms of GSK-3. The results indicate that depending on the stimulatory context, the activity of GSK-3 can be modulated either by growth factors that work through the phosphatidylinositol 3-kinase-protein kinase B cascade or by hormonal stimulation of G protein-coupled receptors that link to changes in intracellular cAMP levels.
Mesh Terms:
Animals, Calcium-Calmodulin-Dependent Protein Kinases, Cell Line, Cyclic AMP, Cyclic AMP-Dependent Protein Kinases, Enzyme Activation, Glycogen Synthase Kinase 3, Glycogen Synthase Kinases, Humans, Phosphatidylinositol 3-Kinases, Phosphorylation, Protein Binding, Protein-Serine-Threonine Kinases, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-akt
Proc. Natl. Acad. Sci. U.S.A.
Date: Oct. 24, 2000
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