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Updated: Mar 19, 2026

Detection of Small GTPase Prenylation and GTP Binding Using Membrane Fractionation and GTPase-linked Immunosorbent Assay
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Inhibition of Ral GTPases Using a Stapled Peptide Approach

Jemima C Thomas1, Jonathan M Cooper2, Natasha S Clayton3

  • 1From the Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom, Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom.

The Journal of Biological Chemistry
|June 24, 2016
PubMed

Insights

Researchers developed novel stapled peptides to target the Ras-RalGEF-Ral pathway, a crucial driver of cancer. This breakthrough offers a new therapeutic strategy for inhibiting cancer cell processes driven by RalB.

Area of Science:

  • Oncology
  • Molecular Biology
  • Drug Discovery

Background:

  • Aberrant Ras signaling is a key driver in many cancers, necessitating new therapeutic inhibitors.
  • Directly targeting activated Ras proteins is challenging, shifting focus to downstream signaling pathways like Ras-Raf, Ras-PI3K, and Ras-RalGEF-Ral.
  • The Ras-RalGEF-Ral pathway remains a difficult target for conventional drug development, with limited inhibitors available.

Purpose of the Study:

  • To design and characterize novel therapeutic agents targeting the Ras-RalGEF-Ral pathway.
  • To develop inhibitors that selectively bind to active, GTP-bound Ral proteins.
  • To provide a starting point for the therapeutic inhibition of RalB-driven cellular processes in cancer.

Main Methods:

  • Utilized the structure of a Ral-effector complex to design α-helical-stapled peptides.
  • Biophysically characterized the designed peptides for selectivity and binding affinity.
  • Assessed the cellular uptake and biological activity of the lead peptide in inhibiting RalB-driven processes.

Main Results:

  • Successfully designed and characterized α-helical-stapled peptides that selectively bind to active Ral proteins.
  • The lead peptide demonstrated cell permeability and biological activity.
  • The peptide inhibited isoform-specific RalB-driven cellular processes.

Conclusions:

  • Developed a novel class of stapled peptides as potential therapeutics for targeting the Ras-RalGEF-Ral pathway.
  • These peptides represent a promising starting point for developing drugs against RalB-driven cancers.
  • This work opens new avenues for inhibiting previously undruggable cancer targets.
Keywords:
RalRasautophagycell signalingpeptide chemical synthesispeptidesprotein-protein interactionsmall GTPasestapled peptidestherapeutics

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