Related Experiment Video
Updated: Jul 19, 2026
10:50
Isolation of Labile Multi-protein Complexes by in vivo Controlled Cellular Cross-Linking and Immuno-magnetic Affinity Chromatography
Published on: March 9, 2010
Cage-like complexes formed by DOTAP, Quil-A and cholesterol
D G Lendemans1, A M Egert, S Hook
1School of Pharmacy, University of Otago, Dunedin, New Zealand.
International Journal of Pharmaceutics
|October 20, 2006
Summary
Researchers explored replacing phospholipid components in immune-stimulating complexes (ISCOMs) with cationic lipid dioleoyl-trimethyl-ammonium-propane (DOTAP). Results indicate DOTAP is unsuitable for creating cationic ISCOM equivalents due to phase separation issues.
Area of Science:
- Biotechnology
- Materials Science
- Immunology
Background:
- Classical immune-stimulating complexes (ISCOMs) utilize phospholipid components for self-assembly.
- There is interest in developing cationic ISCOMs for potential therapeutic applications.
Purpose of the Study:
- To investigate the substitution of phospholipids with the cationic lipid dioleoyl-trimethyl-ammonium-propane (DOTAP) in ISCOM formulations.
- To characterize the self-assembled colloidal structures formed by DOTAP, Quil-A, and cholesterol.
Main Methods:
- Preparation of self-assembled structures using lipid-film hydration and dialysis techniques.
- Characterization of colloidal particles via transmission electron microscopy and laser Doppler velocimetry.
- Analysis of particle zeta-potential and identification of phase separation phenomena.
Main Results:
- Cage-like structures containing DOTAP were successfully formed using the dialysis method, particularly at low DOTAP weight proportions (<25%).
- Compositions with high DOTAP proportions (>25%) exhibited significant phase separation, hindering the formation of stable structures.
- Particles formed with low DOTAP content displayed neutral to negative zeta-potentials, not the desired cationic charge.
Conclusions:
- While DOTAP can be incorporated into Quil-A and cholesterol to form cage-like particles, it is not suitable for preparing cationic ISCOM equivalents.
- The observed phase separation and lack of cationic charge limit the utility of DOTAP in this context.
Related Concept Videos
00:59Mechanisms of Membrane Domain Formation
Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains are formed due to protein-protein interactions, whereas others are formed due to the presence of specific lipids such as sphingolipids and sterols—for example, large proteins, such as bacteriorhodopsin, aggregate and create distinct domains.
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
Another mechanism for membrane domain formation involves membrane proteins interacting with cytoskeletal...
01:12Clathrin Coated Vesicles
Clathrin-coated vesicles use endocytosis to transport receptors and lysosomal hydrolases from the Golgi to the lysosome in the late secretory pathway. Clathrin-mediated endocytosis was the first described endocytic process, and Clathrin-coated vesicles remain one of the most well-studied transport vesicles. The molecular machinery that generates clathrin-coated vesicles comprises over 50 proteins that precisely coordinate vesicle formation. Cell surface receptors concentrated in indented sites...
01:18Membrane Domains
The membrane domains concentrate specific lipids and proteins at one place within the membrane, which helps in cell signaling, adhesion, and other critical cellular processes. These domains can differ in size, composition, function, and lifespan.
Protein Domains
The membrane comprises a group of distinct proteins responsible for carrying out a cell's specific function. For example, the plasma membrane of the human sperm, or a single germ cell, contains a unique set of proteins in the anterior...
Protein Domains
The membrane comprises a group of distinct proteins responsible for carrying out a cell's specific function. For example, the plasma membrane of the human sperm, or a single germ cell, contains a unique set of proteins in the anterior...
01:30Assembly of Signaling Complexes
Multiprotein signaling complexes are formed in a dynamic process involving protein-protein interactions at the cytoplasmic domain of transmembrane receptors or enzymatic and non-enzymatic proteins associated with the receptor. These complexes ensure the activation and propagation of intracellular signals that regulate cell functions.
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
Interaction domains in cell signaling
Interaction domains recognize exposed features of their binding partners containing post-translationally modified sequences,...
01:19Complexation Equilibria: The Chelate Effect
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
02:41Protein Complex Assembly
Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types. Most protein complexes self-assemble spontaneously via ordered pathways, while some proteins need assembly factors that guide their proper assembly. Despite the crowded intracellular environment, proteins usually interact with their correct partners and form functional complexes.
Many viruses self-assemble into a fully functional unit using the infected host cell to...
Many viruses self-assemble into a fully functional unit using the infected host cell to...