Abstract
The Raf-1 serine/threonine kinase is a key component of the MAP kinase cascade, regulating both proliferation and commitment to cell fate. Raf activation is stimulated following its translocation to the plasma membrane, a process that ordinarily requires interaction with the membrane-localized GTPase, Ras-GTP. To investigate the mechanisms underlying Raf activation, we have developed a coumermycin-induced chemical dimerization method. We find that dimerization is by itself sufficient, in the absence of any membrane components, both to activate a modified Raf protein and to stimulate the MAP kinase cascade appropriately. As Ras-GTP-induced membrane localization increases the effective intracellular Raf concentration, our results indicate that homotypic oligomerization may ordinarily act to promote Raf activation in vivo.
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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Aminocoumarins
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Animals
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Biopolymers
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Cell Line
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Cell Membrane / enzymology
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Coumarins / chemistry
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Coumarins / pharmacology
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DNA Gyrase
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DNA Topoisomerases, Type II / metabolism
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Enzyme Activation
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MAP Kinase Kinase 1
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Mice
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Mitogen-Activated Protein Kinase Kinases*
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Molecular Structure
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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Protein-Tyrosine Kinases / metabolism
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Proto-Oncogene Proteins / genetics
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Proto-Oncogene Proteins / metabolism*
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Proto-Oncogene Proteins c-raf
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Streptomyces
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Transfection
Substances
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Aminocoumarins
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Biopolymers
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Coumarins
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Proto-Oncogene Proteins
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Recombinant Fusion Proteins
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Protein-Tyrosine Kinases
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Protein Serine-Threonine Kinases
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Proto-Oncogene Proteins c-raf
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MAP Kinase Kinase 1
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Map2k1 protein, mouse
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Mitogen-Activated Protein Kinase Kinases
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DNA Gyrase
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DNA Topoisomerases, Type II
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coumermycin