Format

Send to:

Choose Destination
See comment in PubMed Commons below
Nature. 1993 Jul 22;364(6435):352-5.

Direct interaction of Ras and the amino-terminal region of Raf-1 in vitro.

Author information

  • 1Imperial Cancer Research Fund, London, UK.

Abstract

The Ras proteins are key regulators of the growth of eukaryotic cells, but their direct target enzymes, or 'effectors', are unknown. The protein encoded by the c-raf-1 proto-oncogene is thought to function downstream of p21ras because disruption of Raf blocks signalling by Ras in a number of systems. Here we report that the amino-terminal cysteine-rich regulatory region of p74c-raf-1 expressed as a glutathione-S-transferase (GST) fusion protein binds directly to Ras with relatively high affinity (50 nM). The binding is strictly dependent on the Ras protein being in the active GTP-bound conformation rather than the inactive GDP-bound state. Raf-GST interacts with wild-type and oncogenic Ras (Val 12) but fails to interact with a biologically inert effector mutant of Ras (Ala 38) and a dominant negative mutant (Asn 17). A peptide based on the effector region of Ras inhibits the interaction. Raf-GST acts as a potent competitive inhibitor of the GTPase-activating proteins p120GAP and neurofibromin. In addition, Raf itself displays weak GTPase-stimulating activity towards Ras. It is therefore likely that Raf is a direct effector of Ras.

PMID:
8332195
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Nature Publishing Group
    Loading ...
    Write to the Help Desk