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Identification of the guanine nucleotide dissociation stimulator for Ral as a putative effector molecule of R-ras, H-ras, K-ras, and Rap.

To identify proteins that bind to the Ras-related protein R-ras we performed a yeast two-hybrid cDNA library screen. Several clones were obtained encoding the C-terminal region of the guanine nucleotide dissociation stimulator for Ral (RalGDS). The R-ras-binding domain of RalGDS (RalGDS-RBD) is distinct from the conserved catalytic exchange factor regions. Using the two-hybrid system, we show that RalGDS-RBD interacts with H-ras, K-ras, and Rap, and with active but not with inactive point mutants of these Ras-like GTPases. Moreover, using purified proteins, we demonstrate the direct GTP-dependent interaction of the Ras-like GTPases with RalGDS-RBD and full-length RalGDS in vitro. Furthermore, we show that RalGDS-RBD and the Ras-binding domain of Raf-1 compete for binding to the Ras-like GTPases. These data indicate that RalGDS is a putative effector molecule for R-ras, H-ras, K-ras, and Rap.

Pubmed ID: 7809086


  • Spaargaren M
  • Bischoff JR


Proceedings of the National Academy of Sciences of the United States of America

Publication Data

December 20, 1994

Associated Grants


Mesh Terms

  • Amino Acid Sequence
  • Animals
  • GTP Phosphohydrolases
  • GTP-Binding Proteins
  • Guanosine Triphosphate
  • Humans
  • Mice
  • Molecular Sequence Data
  • Protein Binding
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-raf
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Signal Transduction
  • ral GTP-Binding Proteins
  • ral Guanine Nucleotide Exchange Factor
  • rap GTP-Binding Proteins
  • ras Proteins