Grb2 adaptor undergoes conformational change upon dimerization

Caleb B. McDonald, Kenneth L. Seldeen, Brian J. Deegan, Marc S. Lewis, Amjad Farooq

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Grb2 is an adaptor protein that couples activated receptor tyrosine kinases to downstream effector molecules such as Ras and Akt. Despite being a central player in mitogenic signaling and a target for therapeutic intervention, the role of Grb2 oligomerization in cellular signaling is not well understood. Here, using the techniques of size-exclusion chromatography, mass spectrometry, analytical ultra-centrifugation and isothermal titration calorimetry, we demonstrate that Grb2 exists in monomer-dimer equilibrium in solution and that the dissociation of dimer into monomers is entropically-driven without an unfavorable enthalpic change at physiological temperatures. Our data indicate that enthalpy and entropy of dimer dissociation are highly temperature-dependent and largely compensate each other resulting in negligible effect of temperature on the overall free energy. From the plot of enthalpy change versus temperature, the magnitude of heat capacity change derived is much smaller than that expected from the rather large molecular surfaces becoming solvent-occluded upon Grb2 dimerization, implying that Grb2 monomers undergo conformational rearrangement upon dimerization. 3D structural models of Grb2 dimer and monomers suggest strongly that such conformational rearrangement upon dimerization may arise from domain swapping. Taken together, our study provides novel insights into the role of Grb2 as an adaptor in cellular signaling circuitry and how Grb2 dimerization may impart high fidelity in signal transduction as well as lead to rapid signal amplification upon receptor stimulation.

Original languageEnglish
Pages (from-to)25-35
Number of pages11
JournalArchives of Biochemistry and Biophysics
Volume475
Issue number1
DOIs
StatePublished - Jul 1 2008

Fingerprint

Dimerization
Dimers
Monomers
Cell signaling
Temperature
Enthalpy
Signal transduction
Oligomerization
Calorimetry
Size exclusion chromatography
Structural Models
Receptor Protein-Tyrosine Kinases
Entropy
Titration
Centrifugation
Free energy
Specific heat
Gel Chromatography
Mass spectrometry
Amplification

Keywords

  • Analytical ultra-centrifugation
  • Grb2 dimerization
  • Isothermal titration calorimetry
  • Mass spectrometry
  • Size-exclusion chromatography

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Cite this

Grb2 adaptor undergoes conformational change upon dimerization. / McDonald, Caleb B.; Seldeen, Kenneth L.; Deegan, Brian J.; Lewis, Marc S.; Farooq, Amjad.

In: Archives of Biochemistry and Biophysics, Vol. 475, No. 1, 01.07.2008, p. 25-35.

Research output: Contribution to journalArticle

McDonald, Caleb B. ; Seldeen, Kenneth L. ; Deegan, Brian J. ; Lewis, Marc S. ; Farooq, Amjad. / Grb2 adaptor undergoes conformational change upon dimerization. In: Archives of Biochemistry and Biophysics. 2008 ; Vol. 475, No. 1. pp. 25-35.
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