Signaling pathways mediated by the mitogen-activated protein (MAP) kinase kinase/MAP kinase cascade.
Mitogen-activated protein (MAP) kinase and its direct activator, MAP kinase kinase (MAPKK), comprise the MAPKK/MAP kinase cascade, which may play a pivotal role in a variety of intracellular signal transduction pathways from yeast to human. Vertebrate MAPKK, a dual-specificity kinase, is activated by serine phosphorylation catalyzed by upstream serine/threonine kinases, MAPKK kinases (MAPKK-Ks). MAPKK is, on the other hand, threonine phosphorylated by MAP kinase, although a physiological role of this MAP kinase-mediated phosphorylation of MAPKK is unknown. Biochemical fractionation of extracts from Xenopus mature oocytes revealed two major and one minor peaks for the MAPKK-K activity. One of the major peaks contained a proto-oncogene product c-Mos, while the other peaks did not. These observations, together with a recent finding that several MAPKK-Ks such as Raf-1 and MEKK may function within a cell, suggest a diversity of MAPKK-Ks. A variety of extracellular signals converge at the MAPKK/MAP kinase cascade through different MAPKK-Ks and elicit a wide spectrum of cellular responses. Therefore, mechanisms that control activation of the MAP kinase cascade temporally and spatially may be important for specification of cellular responses.
Department of Genetics and Molecular Biology, Kyoto University, Japan.
S
S
Matsuda
Y
Y
Gotoh
E
E
Nishida
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D002478:Cells, Cultured; D004789:Enzyme Activation; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases; D010766:Phosphorylation; D011494:Protein Kinases / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000502:physiology; D017231:Proto-Oncogene Proteins c-mos / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf; D011994:Recombinant Proteins; D015398:Signal Transduction / Q000502:physiology*; D014981:Xenopus / Q000196:embryology; D015003:Yeasts / Q000201:enzymology
C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D017231:Proto-Oncogene Proteins c-mos; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases