RalGDS-like factor (Rlf) is a novel Ras and Rap 1A-associating protein

Oncogene. 1996 Jul 18;13(2):353-62.


The small GTPase Rap 1A is a close relative of Ras that, when overexpressed, is able to revert oncogenic transformation induced by active Ras. We screened a mouse embryonic cDNA library using the yeast two-hybrid system and isolated the cDNA of a novel Rap 1A-interacting protein. The open reading frame encodes for an 84 kDa protein with a Cdc25-homology domain which shares approximately 30% identity with Ral guanine nucleotide dissociation stimulator (RalGDS) and RalGDS-like (Rg1). The C-terminal region reveals a striking conservation of sequences with the Ras-binding domain of RalGDS. We designated this protein Rlf, for RalGDS-like factor. In the yeast system, Rlf interacts with Rap 1A, H-Ras and R-Ras, but not with Rac and Rho. In addition, we found that Rlf interacts with Rap 1Aval12 but not with Rap 1AAsn17. In vitro binding studies revealed that a C-terminally located 91 amino acid region of Rlf is sufficient for direct association with the GTP-bound form of Ras and Rap 1A. The observed dissociation constants are 0.6 microM and 0.4 microM, respectively. No significant association with Ras-GDP or Rap 1A-GDP could be detected. These binding characteristics indicate that Rlf is a putative effector for Ras and Rap 1A.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism
  • Cloning, Molecular
  • DNA, Complementary / genetics*
  • DNA, Complementary / isolation & purification*
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • GTP-Binding Proteins / genetics*
  • GTP-Binding Proteins / isolation & purification*
  • GTP-Binding Proteins / metabolism
  • Guanine Nucleotide Exchange Factors*
  • Guanosine Triphosphate / metabolism
  • Mice
  • Molecular Sequence Data
  • Protein Binding
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins
  • Sequence Homology, Amino Acid
  • Transcription Factors / genetics*
  • Transcription Factors / isolation & purification*
  • Transcription Factors / metabolism
  • ral Guanine Nucleotide Exchange Factor
  • rap GTP-Binding Proteins
  • ras Proteins / genetics*
  • ras Proteins / isolation & purification*
  • ras Proteins / metabolism
  • ras-GRF1*


  • CDC25 protein, S cerevisiae
  • Cell Cycle Proteins
  • DNA, Complementary
  • Fungal Proteins
  • Guanine Nucleotide Exchange Factors
  • RGL1 protein, human
  • Rgl1 protein, mouse
  • Rgl2 protein, mouse
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • ral Guanine Nucleotide Exchange Factor
  • ras-GRF1
  • Guanosine Triphosphate
  • GTP-Binding Proteins
  • rap GTP-Binding Proteins
  • ras Proteins

Associated data

  • GENBANK/T08669
  • GENBANK/U54639