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Updated: Jun 17, 2026
11:11
Determination of Plasma Membrane Partitioning for Peripherally-associated Proteins
Published on: June 15, 2018
The plasma membrane consists of two polar-nonpolar-polar leaflets
1Institute of Medical and Physiological Chemistry, Biomedical Center, University of Uppsala, Uppsala, Sweden.
Upsala Journal of Medical Sciences
|January 19, 2010
Summary
This study proposes a double polar-nonpolar-polar leaflet model for plasma membranes, offering a new interpretation of experimental data. This model better explains membrane structure and protein localization than the fluid mosaic model.
Area of Science:
- Cell Biology
- Biophysics
- Membrane Structure
Background:
- The fluid mosaic model has been the prevailing theory for cell membrane structure.
- Alternative models are needed to explain complex experimental observations.
Purpose of the Study:
- To investigate the implications of a double polar-nonpolar-polar leaflet construction for plasma membrane structure.
- To provide a new interpretive framework for experimental data on membrane composition and organization.
Main Methods:
- Transmission electron microscopy (TEM)
- Enzymatic characterization
- X-ray diffraction
- Electron spin resonance (ESR) spectroscopy
- Vectorial digestion and labeling
- Freeze-fracture electron microscopy
Main Results:
- The double polar-nonpolar-polar leaflet model offers advantageous interpretations of TEM and enzymologic data.
- ESR data inconsistent with statistical distribution of spin labels challenge the fluid mosaic model.
- Vectorial digestion, labeling, and freeze-fracture data support the proposed leaflet model.
- Human erythrocyte membrane analysis suggests band III protein and glycophorin in the outer leaflet, and spectrins in the inner leaflet.
Conclusions:
- The double polar-nonpolar-polar leaflet model provides a viable alternative to the fluid mosaic model for plasma membrane structure.
- Specific proteins are localized to distinct leaflets, contributing to membrane asymmetry and function.
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