title: Tyrosine dephosphorylation and concurrent inactivation of protein kinase FA/GSK-3 alpha by genistein in A431 cells.
abstract: Modulation of protein kinase FA/GSK-3 alpha by tyrosine phosphorylation in A431 cells was investigated. Kinase FA/GSK-3 alpha was found to exist in a highly tyrosine-phosphorylated/activated state in resting cells but could become tyrosine-dephosphorylated and inactivated down to less than 30% of control values in a concentration-dependent manner by 50-400 microM genistein (a specific tyrosine kinase inhibitor), as demonstrated by metabolic 32P-labeling of the cells followed by immunoprecipitation and two-dimensional phosphoamino acid analysis and by immunodetection in an antikinase FA/GSK-3 alpha immunoprecipitate kinase assay. Taken together, the results provide evidence that kinase FA/GSK-3 alpha may exist in a highly tyrosine-phosphorylated/activated state in resting cells which can be tyrosine-dephosphorylated and inactivated by extracellular stimulus and that tyrosine kinase(s) and/or tyrosine phosphatase(s) may play a role in the modulation of kinase FA/GSK-3 alpha activity in cells.
authors: Institute of Biomedical Sciences, National Tsing Hua University, Hsinchu, Taiwan, Republic of China.
authors: J S
authors: JS
authors: Yu
authors: S D
authors: SD
authors: Yang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000302:isolation & purification; D001921:Brain / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D002460:Cell Line; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D019833:Genistein; D038362:Glycogen Synthase Kinase 3; D006801:Humans; D015151:Immunoblotting; D007529:Isoflavones / Q000494:pharmacology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000302:isolation & purification; D013552:Swine; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000906:Antibodies; D007529:Isoflavones; D010455:Peptides; D014443:Tyrosine; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3