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.
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
Proc. Natl. Acad. Sci. U.S.A.
Date: Dec. 20, 1994
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