title: Saccharomyces cerevisiae Ste5 is important for induction and substrate specificity of Fus3 MAP kinase in the pheromone signaling pathway.
abstract: The pheromone pathway is one of the mitogen activated protein kinase (MAPK) signaling pathways identified in Saccharomyces cerevisiae and is involved in both G1 cell cycle arrest and mating of cells. Fus3 functions at a branching point for G1 cell cycle arrest and mating responses in the signaling cascade, and the Fus3 MAPK uses components of both G1 arrest and mating routes as substrates. The Ste5 is a scaffold protein of the MAPK module and is essential for the activation of Fus3. However, it is not known how Ste5 is involved in the specific activation of Fus3 in G1 arrest and mating. In this study, we characterized several G1 arrest defective Ste5 mutants to better understand the roles of Ste5 in the regulation of Fus3. The level of Fus3 increased by treatment with alpha-factor. However, the alpha-factor effects were not readily apparent in the observation of yeast cells containing G1 arrest defective ste5 mutant. This suggests that Ste5 plays an essential role in Fus3 induction. Fus3 immune kinase assay of G1 arrest defective ste5 transformants revealed that Ste5 is important for substrate specificity of Fus3 for G1 arrest and/or mating.
authors.affiliation: Department of Biochemistry and Molecular Biology, Institute of Genetic Science, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Choi
authors.forename: S K
authors.initials: SK
authors.lastname: Kim
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.forename: K S
authors.initials: KS
authors.lastname: Lee
authors.forename: K Y
authors.initials: KY
authors.lastname: Choi
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D015153:Blotting, Western; D002352:Carrier Proteins; D002457:Cell Extracts; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D016193:G1 Phase; D020935:MAP Kinase Signaling System; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010675:Pheromones / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013379:Substrate Specificity; D014170:Transformation, Genetic
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D002457:Cell Extracts; D005656:Fungal Proteins; D010675:Pheromones; C080321:STE5 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C075580:FUS3 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases