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Yeast cells arrest in the G1 phase of the cell cycle upon exposure to mating pheromones. As cells commit to a new cycle, G1 CDK activity (Cln/CDK) inhibits signaling through the mating MAPK cascade. Here we show that the target of this inhibition is Ste5, the MAPK cascade scaffold protein. Cln/CDK disrupts Ste5 membrane localization by phosphorylating a(More)
Activation of mitogen-activated protein (MAP) kinase cascade signaling by yeast mating pheromones involves recruitment of the Ste5 scaffold protein to the plasma membrane by the receptor-activated Gbetagamma dimer. Here, we identify a putative amphipathic alpha-helical domain in Ste5 that binds directly to phospholipid membranes and is required for membrane(More)
The Saccharomyces cerevisiae kinase Ste20 is a member of the p21-activated kinase (PAK) family with several functions, including pheromone-responsive signal transduction. While PAKs are usually activated by small G proteins and Ste20 binds Cdc42, the role of Cdc42-Ste20 binding has been controversial, largely because Ste20 lacking its entire Cdc42-binding(More)
CDC42 encodes a highly conserved GTPase of the Rho family that is best known for its role in regulating cell polarity and actin organization. In addition, various studies of both yeast and mammalian cells have suggested that Cdc42p, through its interaction with p21-activated kinases (PAKs), plays a role in signaling pathways that regulate target gene(More)
BACKGROUND Signal transduction pathways with shared components must be insulated from each other to avoid the inappropriate activation of multiple pathways by a single stimulus. Scaffold proteins are thought to contribute to this specificity by binding select substrates. RESULTS We have studied the ability of scaffold proteins to influence signaling by(More)
Distinct MAP kinase pathways in yeast share several signaling components , including the PAK Ste20 and the MAPKKK Ste11, yet signaling is specific. Mating pheromones trigger an initial step in which Ste20 activates Ste11 , and this requires plasma membrane recruitment of the MAP kinase cascade scaffold protein, Ste5 . Here, we demonstrate an additional role(More)
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