Abstract
The mating response pathway of the yeast Saccharomyces cerevisiae includes a heterotrimeric guanine nucleotide-binding protein (G protein) that activates a mitogen-activated protein MAP kinase cascade by an unknown mechanism. An amino-terminal fragment of the MAP kinase scaffold protein Ste5p that interfered with pheromone-induced cell cycle arrest was identified. A haploid-specific interaction between the amino terminus of Ste5p and the G protein beta subunit Ste4p was also detected in a two-hybrid assay, and the product of a signaling-defective allele of STE4 was defective in this interaction. In cells with a constitutively activated pheromone response pathway, epitope-tagged Ste4p was coimmunoprecipitated with Ste5p. Thus, association of the G protein and the MAP kinase cassette via the scaffolding protein Ste5p may transmit the G protein signal.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing*
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Base Sequence
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Calcium-Calmodulin-Dependent Protein Kinases / metabolism
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Carrier Proteins*
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Cell Division
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Fungal Proteins / genetics
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Fungal Proteins / metabolism*
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GTP-Binding Protein beta Subunits*
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GTP-Binding Protein gamma Subunits*
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GTP-Binding Proteins / genetics
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GTP-Binding Proteins / metabolism*
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Heterotrimeric GTP-Binding Proteins*
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Molecular Sequence Data
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Mutation
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Pheromones / pharmacology
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Plasmids
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Saccharomyces cerevisiae / cytology
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins*
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Signal Transduction*
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Transformation, Genetic
Substances
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Adaptor Proteins, Signal Transducing
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Carrier Proteins
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Fungal Proteins
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GTP-Binding Protein beta Subunits
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GTP-Binding Protein gamma Subunits
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Pheromones
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STE18 protein, S cerevisiae
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STE5 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Ste4 protein, S cerevisiae
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Calcium-Calmodulin-Dependent Protein Kinases
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GTP-Binding Proteins
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Heterotrimeric GTP-Binding Proteins