Related Experiment Videos
Peptides containing a consensus Ras binding sequence from Raf-1 and theGTPase activating protein NF1 inhibit Ras
G J Clark1, J K Drugan, R S Terrell
1Department of Pharmacology, University of North Carolina, Chapel Hill, 27599, USA.
Abstract:
A key event in Ras-mediated signal transduction and transformation involves Ras interaction with its downstream effector targets. Although substantial evidence has established that the Raf-1 serine/threonine kinase is a critical effector of Ras function, there is increasing evidence that Ras function is mediated through interaction with multiple effectors to trigger Raf-independent signaling pathways. In addition to the two Ras GTPase activating proteins (GAPs; p120- and NF1-GAP), other candidate effectors include activators of the Ras-related Ral proteins (RalGDS and RGL) and phosphatidylinositol 3-kinase. Interaction between Ras and its effectors requires an intact Ras effector domain and involves preferential recognition of active Ras-GTP. Surprisingly, these functionally diverse effectors lack significant sequence homology and no consensus Ras binding sequence has been described. We have now identified a consensus Ras binding sequence shared among a subset of Ras effectors. We have also shown that peptides containing this sequence from Raf-1 (RKTFLKLA) and NF1-GAP (RRFFLDIA) block NF1-GAP stimulation of Ras GTPase activity and Ras-mediated activation of mitogen-activated protein kinases. In summary, the identification of a consensus Ras-GTP binding sequence establishes a structural basis for the ability of diverse effector proteins to interact with Ras-GTP. Furthermore, our demonstration that peptides that contain Ras-GTP binding sequences can block Ras function provides a step toward the development of anti-Ras agents.
Insights
Researchers identified a shared Ras binding sequence in key signaling proteins, enabling peptide-based disruption of Ras-mediated pathways and offering potential for anti-Ras drug development.
Area of Science:
- Molecular Biology
- Cell Signaling
- Oncology
Background:
- Ras proteins are crucial regulators of cell signaling, mediating signal transduction and cellular transformation.
- While Raf-1 is a known Ras effector, Ras interacts with multiple targets, activating Raf-independent pathways.
- Diverse Ras effectors, including GAPs, RalGDS, RGL, and PI3K, lack apparent sequence homology, complicating understanding of Ras interaction.
Purpose of the Study:
- To identify a consensus Ras binding sequence shared among Ras effector proteins.
- To investigate the functional significance of this consensus sequence in Ras-effector interactions.
- To explore the potential of Ras-binding sequence peptides as therapeutic agents.
Main Methods:
- Sequence analysis to identify conserved motifs in Ras effector proteins.
- Peptide synthesis based on identified consensus sequences from Raf-1 and NF1-GAP.
- In vitro assays to assess the effect of peptides on Ras GTPase activity and downstream signaling.
Main Results:
- A consensus Ras-GTP binding sequence was identified in a subset of Ras effectors.
- Peptides containing this sequence from Raf-1 and NF1-GAP inhibited NF1-GAP-stimulated Ras GTPase activity.
- These peptides also blocked Ras-mediated activation of mitogen-activated protein kinases.
Conclusions:
- The identified consensus sequence provides a structural basis for diverse effector protein interaction with Ras-GTP.
- Peptides targeting this sequence can effectively block Ras effector interactions and downstream signaling.
- This discovery offers a promising strategy for developing novel anti-Ras therapeutic agents.