Glycogen synthase kinase-3 (GSK3) is a protein kinase that was originally identified as a regulator of glycogen synthase, a key enzyme in glycogen metabolism. Since then, it has been shown to be involved in the regulation of a diverse array of cellular functions, including protein synthesis, cell proliferation, cell differentiation, microtubule assembly/disassembly, and apoptosis. GSK3's substrate specificity is unique in that phosphorylation of the substrate only occurs if a phosphoserine or phosphotyrosine is present - four residues C-terminal to the site of GSK phosphorylation. There exists two isoforms of GSK3, GSK3 alpha and GSK3 beta, and they are strictly regulated via phosphorylation. Phosphorylation of GSK3 beta on Ser9 (Ser21 in GSK3alpha) by protein kinase B (PKB) causes its inactivation and is the primary mechanism responsible for growth factor inhibition of this kinase. Activation of GSK3 beta is dependent upon the phosphorylation of Tyr216 (Tyr279 in GSK3 alpha). Upon activation, it has been shown to phosphorylate a number of different cellular proteins, including p53, c-Myc, c-Jun, heat shock factor-1 (HSF-1), and cyclin D1. GSK3 beta also has been shown to phosphorylate aberrant sites on the microtubule associated protein tau, which is critical for the progression of Alzheimer's disease.
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Protein Aliases: FA; Factor A; Glycogen synthase kinase-3 alpha; Glycogen synthase kinase-3 beta; GSK-3 alpha; GSK-3 beta; gsk-3-alpha; GSK3beta isoform; Serine/threonine-protein kinase GSK3A; Serine/threonine-protein kinase GSK3B
Gene Aliases: 2700086H06Rik; 7330414F15Rik; 8430431H08Rik; C86142; GSK-3; GSK-3beta; GSK3; GSK3A; GSK3B