Related Experiment Video
Updated: Aug 13, 2026
06:32
Reconstitution of Septin Assembly at Membranes to Study Biophysical Properties and Functions
Published on: July 28, 2022
Sphingomyelin structure influences the lateral diffusion and raft formation in lipid bilayers
Andrey Filippov1, Greger Orädd, Göran Lindblom
1Department of Biophysical Chemistry, Umeå University, Umeå, Sweden.
Biophysical Journal
|January 3, 2006
Summary
The study investigated how different sphingomyelins (SMs) form membrane domains. Egg SM formed larger domains than brain SM, while milk SM did not form domains, linked to their lipid chain composition.
Area of Science:
- Biophysics
- Membrane Biophysics
- Lipid Bilayer Dynamics
Background:
- Sphingomyelins (SMs) are crucial components of cell membranes, influencing their physical properties.
- The formation of liquid-disordered/liquid-ordered (LD/LO) membrane domains is critical for various cellular functions.
- Understanding the role of SM heterogeneity in domain formation is essential for deciphering membrane organization.
Purpose of the Study:
- To investigate the liquid-disordered/liquid-ordered two-phase coexistence regions in hydrated bilayers of different sphingomyelins (SMs).
- To compare the domain-forming abilities of egg, brain, and milk SMs in multicomponent lipid systems.
- To correlate the observed differences in domain formation with the hydrocarbon chain composition of the SMs.
Main Methods:
- Utilized pulsed-field gradient nuclear magnetic resonance (PFG-NMR) technique.
- Measured lateral diffusion of lipids within hydrated bilayers.
- Investigated both single-component SM bilayers and multicomponent dioleoylphosphatidylcholine/SM/cholesterol systems.
Main Results:
- All three SMs (egg, brain, milk) exhibited similar diffusional behavior in bilayers composed solely of SM.
- In multicomponent systems, the ability to form distinct liquid-ordered and liquid-disordered domains varied significantly among the SMs.
- Egg SM showed a more extended two-phase coexistence area compared to brain SM; milk SM did not exhibit two-phase coexistence.
- These differences correlated with the homogeneity of SM hydrocarbon chain compositions, with egg SM being most homogeneous and milk SM most heterogeneous.
Conclusions:
- The hydrocarbon chain homogeneity of sphingomyelins plays a critical role in their ability to form membrane domains.
- Highly packed bilayers of SM and cholesterol are crucial for domain formation, rather than specific SM-cholesterol interactions.
- The origin of sphingomyelin significantly impacts its behavior in complex lipid bilayers and domain formation.
Related Concept Videos
01:35Asymmetric Lipid Bilayer
Biological membranes show uneven distribution of different types of lipids in the inner and outer layers, resulting in transverse asymmetric membranes. The treatment of the erythrocyte membrane with the enzyme phospholipase confirmed the asymmetric nature of the lipid bilayer. The enzyme hydrolyzes lipids into fatty acids and hydrophilic groups. The phospholipase acts only on the outer layer of the membrane, while the inner layer remains intact. The phospholipase treatment resulted in 80%...
01:26Membrane Fluidity
Membrane fluidity is explained by the fluid mosaic model of the cell membrane, which describes the plasma membrane structure as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character.
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is a relatively...
01:23Membrane Fluidity
Cell membranes are composed of phospholipids, proteins, and carbohydrates loosely attached to one another through chemical interactions. Molecules are generally able to move about in the plane of the membrane, giving the membrane its flexible nature called fluidity. Two other features of the membrane contribute to membrane fluidity: the chemical structure of the phospholipids and the presence of cholesterol in the membrane.Fatty acids tails of phospholipids can be either saturated or...
01:19Fluid Mosaic Model
Scientists identified the plasma membrane in the 1890s and its principal chemical components (lipids and proteins) by 1915. The model for plasma membrane structure, proposed in 1935 by Hugh Davson and James Danielli, was the first model to be widely accepted in the scientific community. The model was based on the plasma membrane's "railroad track" appearance in early electron micrographs. Davson and Danielli theorized that the plasma membrane's structure resembled a sandwich with the analogy of...
01:34Fluid Mosaic Model
The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of membranes and serves as a foundation for future membrane-related studies. The model depicts the structure of the plasma membrane with a variety of components, which include phospholipids, proteins, and carbohydrates. These integral molecules are loosely bound, defining the cell’s border and providing fluidity for optimal function.LipidsThe most...
01:24Protein Diffusion in the Membrane
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...