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 RIS Download
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