title: Activation of the Raf-1 kinase cascade by coumermycin-induced dimerization.
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.
authors.affiliation: Howard Hughes Medical Institute, University of Washington, Seattle, 98195, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Farrar
authors.forename: J
authors.initials: J
authors.lastname: Alberol-Ila
authors.forename: R M
authors.initials: RM
authors.lastname: Perlmutter
mesh_terms: D016475:3T3 Cells; D049933:Aminocoumarins; D000818:Animals; D001704:Biopolymers; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D003374:Coumarins / Q000737:chemistry / Q000494:pharmacology; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004789:Enzyme Activation; D048369:MAP Kinase Kinase 1; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases; D015394:Molecular Structure; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013302:Streptomyces; D014162:Transfection
chemical_list: D049933:Aminocoumarins; D001704:Biopolymers; D003374:Coumarins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D048369:MAP Kinase Kinase 1; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II; C004628:coumermycin