The CDC25 protein of Saccharomyces cerevisiae promotes exchange of guanine nucleotides bound to ras

Mol Cell Biol. 1991 May;11(5):2641-6. doi: 10.1128/mcb.11.5.2641-2646.1991.


The product of the CDC25 gene of Saccharomyces cerevisiae, in its capacity as an activator of the RAS/cyclic AMP pathway, is required for initiation of the cell cycle. In this report, we provide an identification of Cdc25p, the product of the CDC25 gene, and evidence that it promotes exchange of guanine nucleotides bound to Ras in vitro. Extracts of strains containing high levels of Cdc25p catalyze both removal of GDP from and the concurrent binding of GTP to Ras. This same activity is also obtained with an immunopurified Cdc25p-beta-galactosidase fusion protein, suggesting that Cdc25p participates directly in the exchange reaction. This biochemical activity is consistent with previous genetic analysis of CDC25 function.

Publication types

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

MeSH terms

  • Cell Cycle Proteins*
  • Cell Membrane / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / isolation & purification
  • Fungal Proteins / metabolism*
  • Genotype
  • Guanosine Diphosphate / metabolism*
  • Guanosine Triphosphate / metabolism*
  • Kinetics
  • Molecular Weight
  • Protein Binding
  • Recombinant Fusion Proteins / isolation & purification
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins
  • ras Proteins*
  • ras-GRF1*


  • CDC25 protein, S cerevisiae
  • Cell Cycle Proteins
  • Fungal Proteins
  • Recombinant Fusion Proteins
  • Saccharomyces cerevisiae Proteins
  • ras-GRF1
  • Guanosine Diphosphate
  • Guanosine Triphosphate
  • ras Proteins