Spaargaren M, Martin G A, McCormick F, Fernandez-Sarabia M J, Bischoff J R
ONYX Pharmaceuticals, Richmond, CA 94806.
Biochem J. 1994 Jun 1;300 ( Pt 2)(Pt 2):303-7. doi: 10.1042/bj3000303.
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.
R-ras是小GTP酶Ras家族的成员，与凋亡抑制原癌基因产物Bcl-2相关。我们利用酵母双杂交系统为R-ras与Raf-1激酶之间的相互作用提供了证据。这种相互作用仅需要Raf-1的N端调节结构域（氨基酸1-256），并且在野生型和组成型活性R-ras突变体中均观察到，但在缺乏潜在效应结构域的缺失突变体或GTP结合受损的R-ras突变体中未观察到。此外，使用体外结合试验，我们展示了纯化的R-ras与对应于Raf-1提议的81个氨基酸的H-Ras结合结构域（氨基酸51-131）的纯化Raf-1片段之间直接的GTP依赖性相互作用。综上所述，这些数据表明R-ras可能通过调节Raf-1激酶作为其直接下游效应器的活性来发挥其生物学效应。
