RNA aptamers that hind to the Ras-binding domain (RBD) of a proto-oncogene
product, Raf-1, were isolated from a pool of random sequences using a gluta
thione S-transferase-fused RBD (GST-RBD), The RNA molecules bind to the GST
-RBD, but not to GST, with dissociation constants of about 300 nM. In contr
ast, these RNA aptamers do not bind to the Res-binding domain of the RGL pr
otein, which is also known to be activated by Ras, The aptamers actually co
mpete with Ras for binding to the Raf-1 RBD. The anti-Raf-1 aptamers may be
used to specifically inhibit the Ras-Raf interaction in the complicated si
gnaling network in mammalian cells. (C) 1998 Federation of European Biochem
ical Societies.