Osmotic activation of the HOG MAPK pathway via Ste11p MAPKKK: scaffold role of Pbs2p MAPKK.
Exposure of the yeast Saccharomyces cerevisiae to high extracellular osmolarity induces the Sln1p-Ypd1p-Ssk1p two-component osmosensor to activate a mitogen-activated protein (MAP) kinase cascade composed of the Ssk2p and Ssk22p MAP kinase kinase kinases (MAPKKKs), the Pbs2p MAPKK, and the Hog1p MAPK. A second osmosensor, Sho1p, also activated Pbs2p and Hog1p, but did so through the Ste11p MAPKKK. Although Ste11p also participates in the mating pheromone-responsive MAPK cascade, there was no detectable cross talk between these two pathways. The MAPKK Pbs2p bound to the Sho1p osmosensor, the MAPKKK Ste11p, and the MAPK Hog1p. Thus, Pbs2p may serve as a scaffold protein.
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Division of Tumor Immunology, Dana-Farber Cancer Institute, Boston, MA 02115, USA.
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D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D020930:MAP Kinase Kinase Kinases; D000072235:Mating Factor; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D009154:Mutation; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D010455:Peptides / Q000378:metabolism; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction
D010455:Peptides; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; D020930:MAP Kinase Kinase Kinases; C067018:Ste11 protein, S cerevisiae; D020929:Mitogen-Activated Protein Kinase Kinases; C089356:PBS2 protein, S cerevisiae