Related Experiment Video

Updated: Jul 2, 2025

Comparing the Affinity of GTPase-binding Proteins using Competition Assays
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Comparing the Affinity of GTPase-binding Proteins using Competition Assays

Published on: October 8, 2015

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Conserved allosteric perturbation of the GTPase domains by region 1 of Ras hypervariable regions

Xue Gu1, Yalong Zhang1, Dong Long2

  • 1MOE Key Laboratory for Cellular Dynamics, School of Life Sciences, University of Science and Technology of China, Hefei, China.

Biophysical Journal
|February 29, 2024
PubMed

Insights

Ras proteins

Area of Science:

  • Molecular biology
  • Cell signaling
  • Protein structure and dynamics

Background:

  • Ras proteins are key regulators of intracellular signaling pathways.
  • Their GTPase domains (G-domains) interact with effectors and regulators.
  • C-terminal hypervariable regions (HVRs) anchor Ras to plasma membranes, but their regulatory role is debated.

Purpose of the Study:

  • To investigate the mechanism and specificity of intramolecular interactions between Ras G-domains and HVRs.
  • To elucidate how HVRs regulate Ras protein function.

Main Methods:

  • Nuclear Magnetic Resonance (NMR) spectroscopy, specifically chemical shift perturbations.
  • Membrane paramagnetic relaxation enhancement (mPRE) to study membrane interactions and orientations.
  • Analysis of Ras isoforms (HRas and KRas4B) and different nucleotide-bound states.

Main Results:

  • Ras HVRs weakly perturb G-domains via a conserved, short-range allosteric interaction (∼20 Å).
  • This perturbation originates from a specific segment (residues 167-171) within the HVRs.
  • A cancer-associated mutation (E168K) in this segment mimics HVR truncation effects, altering membrane orientation and increasing the signaling-competent state.

Conclusions:

  • Ras HVRs regulate G-domain conformation and membrane interaction through a conserved allosteric mechanism.
  • This interaction is crucial for modulating Ras signaling activity.
  • The findings provide insights into Ras regulation and the functional impact of cancer mutations.

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