title: Ste50p sustains mating pheromone-induced signal transduction in the yeast Saccharomyces cerevisiae.
abstract: In the yeast Saccharomyces cerevisiae, the heterotrimeric G protein transduces the mating pheromone signal from a cell-surface receptor. Free G beta gamma then activates a mitogen-activated protein (MAP) kinase cascade. STE50 has been shown to be involved in this pheromone signal-transduction pathway. In this study, we present a functional characterization of Ste50p, a protein that is required to sustain the pheromone-induced signal which leads cells to hormone-induced differentiation. Inactivation of STE50 leads to the attenuation of mating pheromone-induced signal transduction, and overexpression of STE50 intensifies the pheromone-induced signalling. By genetic analysis we have positioned the action of Ste50p downstream of the alpha-pheromone receptor (STE2), at the level of the heterotrimeric G protein, and upstream of STE5 and the kinase cascade of STE11 and STE7. In a two-hybrid assay Ste50p interacts weakly with the G protein and strongly with the MAPKKK Ste11p. The latter interaction is absent in the constitutive mutant Ste11pP279S. These data show that a new component, Ste50p, determines the extent and the duration of signal transduction by acting between the G protein and the MAP kinase complex in S. cerevisiae.
authors.affiliation: Institut für Mikrobiologie, Heinrich-Heine-Universität Düsseldorf, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Xu
authors.forename: G
authors.initials: G
authors.lastname: Jansen
authors.forename: D Y
authors.initials: DY
authors.lastname: Thomas
authors.forename: C P
authors.initials: CP
authors.lastname: Hollenberg
authors.forename: M
authors.initials: M
authors.lastname: Ramezani Rad
mesh_terms: D000483:Alleles; D005656:Fungal Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D000072235:Mating Factor; D010455:Peptides / Q000378:metabolism*; D010675:Pheromones / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D015398:Signal Transduction; D014157:Transcription Factors
chemical_list: D005656:Fungal Proteins; D010455:Peptides; D010675:Pheromones; D051964:Receptors, Mating Factor; D018000:Receptors, Peptide; C079506:STE50 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C071596:ste11 protein, S pombe; D000072235:Mating Factor; D017346:Protein Serine-Threonine Kinases; D020930:MAP Kinase Kinase Kinases; C067018:Ste11 protein, S cerevisiae; D019204:GTP-Binding Proteins