S. cerevisiae genes IRA1 and IRA2 encode proteins that may be functionally equivalent to mammalian ras GTPase activating protein

Cell. 1990 Mar 9;60(5):803-7. doi: 10.1016/0092-8674(90)90094-u.


The IRA1 and IRA2 genes of S. cerevisiae encode closely related proteins that also share homology with mammalian GAP (ras GTPase activating protein). The RAS1 and RAS2 proteins overexpressed in ira mutants accumulated in the GTP-bound form, whereas in the wild-type strain the proteins were found mostly in the GDP-bound form, indicating that IRA1 and IRA2 negatively regulate the level of RAS-GTP. In contrast, the RAS2Val-19 or RAS2Thr-66 mutant protein was bound to GTP in high amounts irrespective of the IRA genotype. Overexpression of bovine GAP suppressed the phenotypes of ira mutants by reducing the level of RAS-GTP, suggesting that IRA proteins may be functionally analogous to mammalian GAP.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism
  • GTPase-Activating Proteins
  • Genes, Fungal*
  • Guanine Nucleotides / metabolism
  • Plasmids
  • Proteins / genetics*
  • Proteins / metabolism
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins*
  • ras GTPase-Activating Proteins
  • ras Proteins*


  • Fungal Proteins
  • GTPase-Activating Proteins
  • Guanine Nucleotides
  • Proteins
  • Saccharomyces cerevisiae Proteins
  • ras GTPase-Activating Proteins
  • RAS1 protein, S cerevisiae
  • RAS2 protein, S cerevisiae
  • ras Proteins