Functional characterization of the Cdc42p binding domain of yeast Ste20p protein kinase

Ekkehard Leberer, Cunle Wu, Thomas Leeuw, Anne Fourest-Lieuvin, Jeffrey E. Segall, David Y. Thomas

Research output: Contribution to journalArticlepeer-review

169 Scopus citations


Ste20p from Saccharomyces cerevisiae belongs to the Ste20p/p65(PAK) family of protein kinases which are highly conserved from yeast to man and regulate conserved mitogen-activated protein kinase pathways. Ste20p fulfills multiple roles in pheromone signaling, morphological switching and vegetative growth and binds Cdc42p, a Rho-like small GTP binding protein required for polarized morphogenesis. We have analyzed the functional consequences of mutations that prevent binding of Cdc42p to Ste20p. The complete amino-terminal, non-catalytic half of Ste20p, including the conserved Cdc42p binding domain, was dispensable for heterotrimeric G-protein-mediated pheromone signaling. However, the Cdc42p binding domain was necessary-for filamentous growth in response to nitrogen starvation and for an essential function that Ste20p shares with its isoform Cla4p during vegetative growth. Moreover, the Cdc42p binding domain was required for cell-cell adhesion during conjugation. Subcellular localization of wild-type and mutant Ste20p fused to green fluorescent protein showed that the Cdc42p binding domain is needed to direct localization of Ste20p to regions of polarized growth. These results suggest that Ste20p is regulated in different developmental pathways by different mechanisms which involve heterotrimeric and small GTP binding proteins.

Original languageEnglish (US)
Pages (from-to)83-97
Number of pages15
JournalEMBO Journal
Issue number1
StatePublished - Jan 2 1997


  • Cdc42p
  • Mating pheromone
  • Signal transduction
  • Ste20p kinase
  • Yeast

ASJC Scopus subject areas

  • General Neuroscience
  • Molecular Biology
  • General Biochemistry, Genetics and Molecular Biology
  • General Immunology and Microbiology


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