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Protein Diffusion in the Membrane

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Proteins show rotational as well as lateral diffusion across the membrane. The lateral diffusion of proteins was confirmed through the cell fusion experiment where mouse and human cells were fused, resulting in hybrid cells. When the human and mouse cells fused, the specific membrane proteins on human and mouse cells were marked with the red and green-fluorescent markers, respectively. Initially, the red and green fluorescence was located on the respective hemisphere of the cell. As time...

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The plasma membrane, a critical structure in cellular biology, houses an array of transporters, or carrier proteins, interspersed within its lipid bilayer. These proteins play a crucial role in solute transport through facilitated diffusion, a form of passive diffusion that uses transporters to move the molecules across the membrane.
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Passive diffusion is a critical process that allows small lipophilic drugs to cross the cell membrane along a concentration gradient. This mechanism's efficiency depends on four primary factors: the membrane's surface area, the drug's lipid-water partition coefficient, the concentration gradient, and the membrane's thickness.
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Related Experiment Video

Updated: Jul 11, 2026

A Method for Determination and Simulation of Permeability and Diffusion in a 3D Tissue Model in a Membrane Insert System for Multi-well Plates

A Method for Determination and Simulation of Permeability and Diffusion in a 3D Tissue Model in a Membrane Insert System for Multi-well Plates

Published on: February 23, 2018

Hindered diffusion in microporous membranes with known pore geometry.

R E Beck, J S Schultz

Science (New York, N.Y.)

|December 18, 1970

Summary

Solute diffusion rates significantly decrease in microporous membranes, even with small molecules. The Renkin equation accurately quantifies this hindrance effect on molecular diffusion.

Area of Science:

Physical Chemistry
Materials Science
Chemical Engineering

Background:

Understanding solute diffusion in porous materials is crucial for applications like filtration and drug delivery.
Previous studies faced challenges with non-uniform pore structures, complicating diffusion analysis.
Accurate determination of molecular diffusion requires well-defined porous systems.

Purpose of the Study:

To precisely quantify the hindrance effect on aqueous solute diffusion within molecular-sized membrane pores.
To investigate the relationship between pore size and molecular diffusion rates using a controlled membrane system.
To validate theoretical models for hindered diffusion in microporous membranes.

Main Methods:

Fabrication of uniform, straight-pored mica membranes (3-5 µm thick, 90-600 Å diameter).

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Published on: August 16, 2016

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Last Updated: Jul 11, 2026

A Method for Determination and Simulation of Permeability and Diffusion in a 3D Tissue Model in a Membrane Insert System for Multi-well Plates

A Method for Determination and Simulation of Permeability and Diffusion in a 3D Tissue Model in a Membrane Insert System for Multi-well Plates

Published on: February 23, 2018

Membrane Transport Processes Analyzed by a Highly Parallel Nanopore Chip System at Single Protein Resolution

Membrane Transport Processes Analyzed by a Highly Parallel Nanopore Chip System at Single Protein Resolution

Published on: August 16, 2016

Measurement of aqueous diffusion rates for solutes with molecular diameters from 5.2 to 43 Å.

Correction for liquid film resistances to determine intrinsic molecular diffusivities within the pores.

Main Results:

Demonstrated a marked decrease in diffusion rates as molecular size approaches pore size, even for small fractions.
Confirmed that diffusion rates are significantly hindered even when solute molecules are much smaller than pore dimensions.
Obtained quantitative estimates of solute diffusivity reduction within the microporous membrane.

Conclusions:

Mica membranes with uniform pores provide a reliable model for studying hindered diffusion.
Molecular size plays a critical role in diffusion rates within microporous membranes.
The Renkin equation effectively models the observed reduction in solute diffusivity in microporous systems.