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Updated: Mar 21, 2026

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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Proteomic analysis of Rac1 signaling regulation by guanine nucleotide exchange factors

Hadir Marei1, Alejandro Carpy2, Boris Macek2

  • 1a Cell Signaling Group, Cancer Research UK Manchester Institute, The University of Manchester , Manchester , UK.

Cell Cycle (Georgetown, Tex.)
|May 7, 2016
PubMed

Insights

The small GTPase Rac1, crucial for cell function and implicated in cancer, exhibits distinct downstream effects based on its activating Guanine nucleotide Exchange Factors (GEFs). GEF-specific Rac1 interactomes explain its opposing cellular roles.

Area of Science:

  • Cellular Biology
  • Molecular Signaling
  • Cancer Research

Background:

  • The small GTPase Rac1 regulates essential cellular processes, and its dysregulation is linked to diseases like cancer.
  • Rac1's diverse functions stem from its interactions with downstream effectors, modulated by Guanine nucleotide Exchange Factors (GEFs).
  • Understanding GEF-mediated specificity in Rac1 signaling is crucial for elucidating its normal and pathological roles.

Purpose of the Study:

  • To identify and characterize Rac1 interactors modulated by specific GEFs (Tiam1 and P-Rex1).
  • To elucidate the molecular mechanisms underlying GEF-dependent Rac1 signaling specificity.
  • To provide insights into signaling cascades driving GEF-mediated cellular effects.

Main Methods:

  • Quantitative proteomic screening to identify Rac1 interactome changes.
  • Functional annotation of differentially regulated Rac1 binding partners.
  • Analysis of signaling cascades involved in GEF-mediated Rac1 effects.

Main Results:

  • Distinct Rac1 interactomes were identified upon activation by Tiam1 (anti-migratory) versus P-Rex1 (pro-migratory).
  • A comprehensive list of Rac1 interactors and their functional annotations were generated.
  • Novel and known signaling pathways contributing to GEF-specific Rac1 functions were highlighted.

Conclusions:

  • GEF-mediated modulation of the Rac1 interactome dictates opposing cellular outcomes, such as migration.
  • This study provides a detailed molecular basis for Rac1 signaling specificity.
  • The findings offer new perspectives on Rac1's role in normal physiology and disease, particularly cancer.
Keywords:
Guanine nucleotide Exchange Factors (GEFs)IQGAP1Ingenuity Integrated Pathway Analysis (IPA)P-Rex1Rac1Small GTPasesStable Isotope Labeling by Amino acids in Cell culture (SILAC)TMOD3Tandem Affinity Purification (TAP)Tiam1

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