Ste5 tethers multiple protein kinases in the MAP kinase cascade required for mating in S. cerevisiae

Cell. 1994 Aug 12;78(3):499-512. doi: 10.1016/0092-8674(94)90427-8.

Abstract

Ste5 is a Zn2+ finger-like protein thought to function before three kinases, Ste11 (a MEKK), Ste7 (a MEK), and Fus3 (a MAPK), in a conserved MAP kinase cascade required for mating in S. cerevisiae. Here, we present evidence that Ste5 forms a multikinase complex that joins these kinases for efficient Fus3 activation. By two-hybrid analysis, Ste11, Ste7, and Fus3 associate with different domains of Ste5, while Kss1, another MAPK, associates with the same domain as Fus3, thus implying that Ste5 simultaneously binds a MEKK, MEK, and MAPK. Ste5 copurifies with Ste11, Fus3, and a hypophosphorylated form of Ste7, and all four proteins cosediment in a glycerol gradient as if in a large complex. Ste5 also increases the amount of Ste11 complexed to Ste7 and Fus3 and is required for Ste11 to function. These results substantiate a novel signal transduction component that physically links multiple kinases within a single cascade.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptor Proteins, Signal Transducing*
  • Base Sequence
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism
  • Carrier Proteins*
  • DNA Mutational Analysis
  • Fungal Proteins / metabolism*
  • MAP Kinase Kinase Kinases / metabolism*
  • Macromolecular Substances
  • Mitogen-Activated Protein Kinase Kinases
  • Mitogen-Activated Protein Kinases*
  • Models, Biological
  • Molecular Sequence Data
  • Protein Binding
  • Protein Kinases / metabolism*
  • Reproduction
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • Schizosaccharomyces pombe Proteins*
  • Signal Transduction*
  • Transcription Factors*

Substances

  • Adaptor Proteins, Signal Transducing
  • Carrier Proteins
  • Fungal Proteins
  • Macromolecular Substances
  • STE5 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Schizosaccharomyces pombe Proteins
  • Transcription Factors
  • ste11 protein, S pombe
  • Protein Kinases
  • Calcium-Calmodulin-Dependent Protein Kinases
  • FUS3 protein, S cerevisiae
  • KSS1 protein, S cerevisiae
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase Kinases
  • Ste11 protein, S cerevisiae
  • Mitogen-Activated Protein Kinase Kinases