Expression and characterization of glycogen synthase kinase-3 mutants and their effect on glycogen synthase activity in intact cells.
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- H Eldar-Finkelman
- Department of Pharmacology, University of Washington, Seattle 98195, USA.
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- G M Argast
- Department of Pharmacology, University of Washington, Seattle 98195, USA.
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- O Foord
- Department of Pharmacology, University of Washington, Seattle 98195, USA.
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- E H Fischer
- Department of Pharmacology, University of Washington, Seattle 98195, USA.
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- E G Krebs
- Department of Pharmacology, University of Washington, Seattle 98195, USA.
書誌事項
- 公開日
- 1996-09-17
- DOI
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- 10.1073/pnas.93.19.10228
- 公開者
- Proceedings of the National Academy of Sciences
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説明
<jats:p>In these studies we expressed and characterized wild-type (WT) GSK-3 (glycogen synthase kinase-3) and its mutants, and examined their physiological effect on glycogen synthase activity. The GSK-3 mutants included mutation at serine-9 either to alanine (S9A) or glutamic acid (S9E) and an inactive mutant, K85,86MA. Expression of WT and the various mutants in a cell-free system indicated that S9A and S9E exhibit increased kinase activity as compared with WT. Subsequently, 293 cells were transiently transfected with WT GSK-3 and mutants. Cells expressing the S9A mutant exhibited higher kinase activity (2.6-fold of control cells) as compared with cells expressing WT and S9E (1.8- and 2.0-fold, respectively, of control cells). Combined, these results suggest serine-9 as a key regulatory site of GSK-3 inactivation, and indicate that glutamic acid cannot mimic the function of the phosphorylated residue. The GSK-3-expressing cell system enabled us to examine whether GSK-3 can induce changes in the endogenous glycogen synthase activity. A decrease in glycogen synthase activity (50%) was observed in cells expressing the S9A mutant. Similarly, glycogen synthase activity was suppressed in cells expressing WT and the S9E mutant (20-30%, respectively). These studies indicate that activation of GSK-3 is sufficient to inhibit glycogen synthase in intact cells, and provide evidence supporting a physiological role for GSK-3 in regulating glycogen synthase and glycogen metabolism.</jats:p>
収録刊行物
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- Proceedings of the National Academy of Sciences
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Proceedings of the National Academy of Sciences 93 (19), 10228-10233, 1996-09-17
Proceedings of the National Academy of Sciences