Ste50p sustains mating pheromone-induced signal transduction in the yeast Saccharomyces cerevisiae.

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.
Mesh Terms:
Alleles, Fungal Proteins, GTP-Binding Proteins, MAP Kinase Kinase Kinases, Peptides, Pheromones, Protein-Serine-Threonine Kinases, Receptors, Mating Factor, Receptors, Peptide, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Schizosaccharomyces pombe Proteins, Signal Transduction, Transcription Factors
Mol. Microbiol.
Date: May. 01, 1996
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