Abstract
Mitogenic and stres signals results in the activation of extracellular signal-regulated kinases (ERKs) and stress-activated protein kinase/c-Jun N-terminal kinases (SAPK/JNKs), respectively, which are two subgroups of the mitogen-activated protein kinases. A nuclear target of mitogen-activated protein (MAP) kinases is the ternary complex factor Elk-1, which underlies its involvement in the regulation of c-fos gene expression by mitogenic and stress signals. A second ternary complex factor, Sap1a, is coexpressed with Elk-1 in several cell types and shares attributes of Elk-1, the significance of which is not clear. Here we show that Sap1a is phosphorylated efficiently by ERKs but not by SAPK/JNKs. Serum response factor-dependent ternary complex formation by Sap1a is stimulated by ERK phosphorylation but not by SAPK/JNKs. Moreover, Sap1a-mediated transcription is activated by mitogenic signals but not by cell stress. These results suggest that Sap1a and Elk-1 have distinct physiological functions.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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3T3 Cells
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Animals
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
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Chloramphenicol O-Acetyltransferase / biosynthesis
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Cloning, Molecular
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DNA-Binding Proteins / metabolism*
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Escherichia coli
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HeLa Cells
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Humans
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JNK Mitogen-Activated Protein Kinases
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MAP Kinase Kinase 4*
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Macromolecular Substances
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Mice
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Mitogen-Activated Protein Kinase Kinases*
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Mitogen-Activated Protein Kinases*
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Phosphorylation
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Protein Kinases / metabolism
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Proto-Oncogene Proteins / metabolism
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Recombinant Fusion Proteins / metabolism
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Sequence Tagged Sites
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Substrate Specificity
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Tetradecanoylphorbol Acetate / pharmacology
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Transcription Factors*
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Transfection
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ets-Domain Protein Elk-1
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ets-Domain Protein Elk-4
Substances
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DNA-Binding Proteins
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ELK1 protein, human
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ELK4 protein, human
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Elk1 protein, mouse
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Elk4 protein, mouse
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Macromolecular Substances
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Proto-Oncogene Proteins
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Recombinant Fusion Proteins
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Transcription Factors
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ets-Domain Protein Elk-1
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ets-Domain Protein Elk-4
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Chloramphenicol O-Acetyltransferase
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Protein Kinases
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Calcium-Calmodulin-Dependent Protein Kinases
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JNK Mitogen-Activated Protein Kinases
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Mitogen-Activated Protein Kinases
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MAP Kinase Kinase 4
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MAP2K4 protein, human
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Map2k4 protein, mouse
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Mitogen-Activated Protein Kinase Kinases
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Tetradecanoylphorbol Acetate