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Updated: Jul 1, 2025
11:11
Determination of Plasma Membrane Partitioning for Peripherally-associated Proteins
Published on: June 15, 2018
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Membrane localization accelerates association under conditions relevant to cellular signaling
William Y C Huang1, Steven G Boxer2, James E Ferrell1,3
1Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305.
Summary
Cell signaling molecules associate faster on the plasma membrane than in the cytoplasm. This membrane kinetic advantage is significant for larger cells but negligible for smaller ones.
Area of Science:
- Cell Biology
- Biophysics
- Molecular Dynamics
Background:
- Translocation of cytoplasmic molecules to the plasma membrane is a key process in cell signaling.
- It is debated whether membrane localization enhances or hinders intermolecular association rates due to diffusion limitations.
Purpose of the Study:
- To directly compare the association rates of DNA strands in solution (cytosol) versus on supported membranes.
- To investigate the impact of cell size on the kinetic advantage of membrane-associated reactions.
Main Methods:
- Utilized complementary DNA strands as a model system for an identical association reaction.
- Compared reaction kinetics in bulk solution (simulating cytosol) and on supported lipid bilayers (simulating plasma membrane).
- Measured rate constants to quantify association efficiency.
Main Results:
- DNA strand association was 22- to 33-fold faster on the membrane compared to the cytosol for a 10-µm-radius cell.
- The kinetic advantage of membrane localization is dependent on cell size.
- The effect was minimal for small, ~1 µm prokaryotic cells.
Conclusions:
- Plasma membrane localization significantly enhances intermolecular association rates in larger cells.
- This enhancement is driven by increased two-dimensional encounter rates and a higher reaction probability per encounter.
- Cellular compartmentalization plays a crucial role in modulating reaction kinetics for biological processes.
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