Pheromone mediated signaling pathway is an essential network for Gl cell cycle arrest and mating of S. cerevisiae. Down stream components of the pathway are well conserved with the components of mammalian MAP (Mitogen activated protein) kinase pathways. Ste5 is a 917 amino acid protein with no known catalytic function and essential for the pheromone signaling pathway. No SteS homologous proteins are found in the MAP kinase dependent signal transduction pathways in higher eukaryotic organisms. Recent studies revealed unique structural role of SteS for proper signal transmission. SteS tethers multi protein kinases (Stell, Ste7, and Fus3) for the activation of the MAP kinase homologue Fus3 and for proper regulation of signal transmission. In this way SteS performs very important role (s) in the signaling pathway, although the detailed roles of SteS is not illustrated yet. To define the roles of SteS more precisely we isolated 95 ctfactor resistant cell cycle arrest mutants of SteS by hydroxylamine mutagenesis of a plasmid bearing myc epitope tagged SteS gene (SteSM). Two plasmids containing noble SteSM mutants (pKC20M69 and pKC20M72) mate equivalent to the wild type when transformed into the SteS deletion mutants although those can't complements G1 cell cycle arrest function. Furthermore, these strains produced normal levels of mutant proteins shown by Western blot analysis. Isolation and characterization of these SteSM mutants substantialize the roles of Ste5 in the pheromone signaling pathway of S. cerevisiae.
|Publication status||Published - 1996|
All Science Journal Classification (ASJC) codes
- Molecular Biology