Protein-protein interactions in the yeast pheromone response pathway: Ste5p interacts with all members of the MAP kinase cascade.
We have used the two-hybrid system of Fields and Song to identify protein-protein interactions that occur in the pheromone response pathway of the yeast Saccharomyces cerevisiae. Pathway components Ste4p, Ste5p, Ste7p, Ste11p, Ste12p, Ste20p, Fus3p and Kss1p were tested in all pairwise combinations. All of the interactions we detected involved at least one member of the MAP kinase cascade that is a central element of the response pathway. Ste5p, a protein of unknown biochemical function, interacted with protein kinases that operate at each step of the MAP kinase cascade, specifically with Ste11p (an MEKK), Ste7p (an MEK), and Fus3p (a MAP kinase). This finding suggests that one role of Ste5p is to serve as a scaffold to facilitate interactions among members of the kinase cascade. In this role as facilitator, Ste5p may make both signal propagation and signal attenuation more efficient. Ste5p may also help minimize cross-talk with other MAP kinase cascades and thus ensure the integrity of the pheromone response pathway. We also found that both Ste11p and Ste7p interact with Fus3p and Kss1p. Finally, we detected an interaction between one of the MAP kinases, Kss1p, and a presumptive target, the transcription factor Ste12p. We failed to detect interactions of Ste4p or Ste20p with any other component of the response pathway.
Department of Chemistry, University of Oregon, Eugene 97403-1229.
J A
JA
Printen
G F
GF
Sprague
D048868:Adaptor Proteins, Signal Transducing; D001483:Base Sequence; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins; D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D020930:MAP Kinase Kinase Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D010675:Pheromones / Q000378:metabolism*; D017354:Point Mutation; D011494:Protein Kinases / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D015398:Signal Transduction; D014157:Transcription Factors
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins; D010675:Pheromones; D011993:Recombinant Fusion Proteins; C080321:STE5 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C071596:ste11 protein, S pombe; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020930:MAP Kinase Kinase Kinases; C067018:Ste11 protein, S cerevisiae