Inhibition of an activated Ras protein with genetically selected peptide aptamers

Biotechnol Bioeng. 2003 Apr 5;82(1):38-46. doi: 10.1002/bit.10538.


Mutant alleles of Ras maintain an activated, GTP-bound conformation and relay mitogenic signals that cannot be turned off. A genetic selection in Saccharomyces cerevisiae was used to identify peptide aptamers that suppress the growth arrest phenotype of an activated Ras allele. Peptide aptamers were expressed as C-terminal fusions to glutathione-S-transferase. Modifications that alter the coding capacity of the peptide aptamer indicate it is necessary for Ras2-Val19 suppression. Aptamer expression also reduces the elevated levels of cAMP and suppresses the heat shock sensitivity characteristic of Ras-activated yeast cells. The peptide aptamer retains suppressor activity when fused to thioredoxin. The peptide aptamer expression strategy described here indicates that aptamers presented as unconstrained peptides have functional capacity in vivo.

MeSH terms

  • Binding Sites / genetics
  • Fungal Proteins*
  • Gene Expression Regulation, Fungal / genetics
  • Genes, Suppressor
  • Ligands
  • Peptide Library
  • Peptides / genetics*
  • Protein Engineering / methods*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • ras Proteins / genetics*
  • ras Proteins / metabolism


  • Fungal Proteins
  • Ligands
  • Peptide Library
  • Peptides
  • Recombinant Proteins
  • Saccharomyces cerevisiae Proteins
  • RAS2 protein, S cerevisiae
  • ras Proteins