A-kinase anchoring protein AKAP220 binds to glycogen synthase kinase-3beta (GSK-3beta ) and mediates protein kinase A-dependent inhibition of GSK-3beta.

Glycogen synthase kinase-3 (GSK-3) is regulated by various extracellular ligands and phosphorylates many substrates, thereby regulating cellular functions. Using yeast two-hybrid screening, we found that GSK-3beta binds to AKAP220, which is known to act as an A-kinase anchoring protein. GSK-3beta formed a complex with AKAP220 in intact cells at the ...
endogenous level. Cyclic AMP-dependent protein kinase (PKA) and type 1 protein phosphatase (PP1) were also detected in this complex, suggesting that AKAP220, GSK-3beta, PKA, and PP1 form a quaternary complex. It has been reported that PKA phosphorylates GSK-3beta, thereby decreasing its activity. When COS cells were treated with dibutyryl cyclic AMP to activate PKA, the activity of GSK-3beta bound to AKAP220 decreased more markedly than the total GSK-3beta activity. Calyculin A, a protein phosphatase inhibitor, also inhibited the activity of GSK-3beta bound to AKAP220 more strongly than the total GSK-3beta activity. These results suggest that PKA and PP1 regulate the activity of GSK-3beta efficiently by forming a complex with AKAP220.
Mesh Terms:
A Kinase Anchor Proteins, Amino Acid Sequence, Animals, Binding Sites, Bucladesine, CHO Cells, Carrier Proteins, Cricetinae, Cyclic AMP-Dependent Protein Kinases, Glycogen Synthase Kinase 3, Humans, Kinetics, Molecular Sequence Data, Peptides, Phosphoprotein Phosphatases, Phosphorylation, Protein Binding, Protein Structure, Quaternary, Recombinant Proteins, Transfection
J. Biol. Chem.
Date: Oct. 04, 2002
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