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Updated: Feb 28, 2026
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Author Spotlight: Evaluation of Protein-Condensate Dynamics in Live Human Cells
Published on: January 5, 2024
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Weak protein-protein interactions in live cells are quantified by cell-volume modulation
Shahar Sukenik1, Pin Ren2, Martin Gruebele3,2,4
1Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
Summary
Cell volume changes can quantify weak protein interactions inside cells. This method reveals the dissociation constant and stoichiometry of the GAPDH:PGK complex in vivo.
Area of Science:
- Biochemistry
- Cell Biology
- Biophysics
Background:
- Weakly bound protein complexes are vital for cellular processes.
- Quantifying these interactions in vivo is challenging due to their low affinity.
Purpose of the Study:
- To develop a method for quantifying weak protein interactions in situ.
- To determine the dissociation constant and stoichiometry of the GAPDH:PGK complex within cells.
Main Methods:
- Rapidly perturbing cell volume by altering osmotic pressure.
- Monitoring protein complex association and dissociation using Förster Resonance Energy Transfer (FRET) microscopy.
- Applying a quantitative model to experimental data.
Main Results:
- Successfully quantified the dissociation constant (log Kd = -9.7 ± 0.3) and stoichiometry (2:1 GAPDH:PGK) of the GAPDH-PGK complex in vivo.
- Demonstrated that cell volume perturbation is effective for studying transient protein interactions.
Conclusions:
- Cellular volume perturbation is a versatile technique for in situ analysis of biomolecular interactions.
- Cells may utilize volume changes to regulate protein complex concentrations and cellular functions.
