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The α‐isoform of glycogen synthase kinase‐3 from rabbit skeletal muscle is inactivated by p70 S6 kinase or MAP kinase‐activated protein kinase‐1 in vitro
Author(s) -
Sutherland Calum,
Cohen Philip
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)80112-6
Subject(s) - p70 s6 kinase 1 , mitogen activated protein kinase kinase , gsk 3 , map2k7 , cyclin dependent kinase 9 , map kinase kinase kinase , cyclin dependent kinase 2 , ask1 , protein kinase a , chemistry , kinase , biochemistry , microbiology and biotechnology , biology , phosphorylation , protein kinase b
The α‐isoform of glycogen synthase kinase‐3 (GSK3α) was inactivated by 80% towards a synthetic peptide substrate upon incubation with Mg‐ATP and either MAP kinase‐activated protein (MAPKAP) kinase‐1 or p70 S6 kinase. Inactivation by either kinase resulted from the phosphorylation of Ser‐21 and was reversed by treatment with protein phosphatase 2A 1 . Phosphorylation also decreased GSK3α activity towards glycogen synthase, inhibitor‐2 and c‐jun. The specificity of GSK3a was similar to GSK3β, but with the synthetic peptide substrate heparin stimulated the dephosphorylated form of GSK3α (6‐fold) more than GSK3β(1.8‐fold). After phosphorylation, both isoforms were stimulated 15–20‐fold by heparin.