R-ras is a member of the ras family of small GTPases that associates with the apoptosis-suppressing proto-oncogene product Bcl-2. Using the yeast two-hybrid system we provide evidence for an interaction between R-ras and the Raf-1 kinase. This interaction requires only the N-terminal regulatory domain (amino acids 1-256) of Raf-1, and is observed with both the wild type and a constitutively active R-ras mutant, but not with a deletion mutant that lacks the potential effector domain or a mutant of R-ras impaired for GTP binding. Moreover, using an in vitro binding assay we show a direct GTP-dependent interaction of purified R-ras with a purified Raf-1 fragment corresponding to the proposed 81-amino-acid H-Ras-binding domain of Raf-1 (amino acids 51-131). Taken together, these data indicate that R-ras may exert its biological effect by means of modulating the activity of the Raf-1 kinase as its direct downstream effector.
The Ras-related protein R-ras interacts directly with Raf-1 in a GTP-dependent manner
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M Spaargaren, G A Martin, F McCormick, M J Fernandez-Sarabia, J R Bischoff; The Ras-related protein R-ras interacts directly with Raf-1 in a GTP-dependent manner. Biochem J 1 June 1994; 300 (2): 303–307. doi: https://doi.org/10.1042/bj3000303
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