Transitions between lamellar and nonlamellar phases in membrane lipids and their physiological roles

Abstract

F : Koynova R, Tenchov B. Transitions between lamellar and non-lamellar phases in membrane lipids and their physiological roles. OA Biochemistry 2013 Apr 01;1(1):9. Abstract Introduction Lipids constitute a large, chemically varied group of biological molecules with diverse biological roles. Their major function is structural—they serve as building blocks of the bio-logical membranes. The aim of this review was to discuss transitions between lamellar and non-lamellar phases in membrane lipids and their physiological roles. Discussion According to the fluid-mosaic model, biomembranes are liquid-crystalline lipid bilayers with embedded proteins. However, in addition to bilayer-form-ing lipids, the lipids in biomembranes include a large fraction of species that, in isolation, adopt curved non-lamellar (hexagonal, cubic etc.) struc-tures rather than the lamellar state. Consequently, except for the lamellar liquid-crystalline phase (the 'mem-brane' phase), the membrane lipids are also able to form a large variety of other phases with different geom-etry and molecular structure. These phases are mutually related and transform into each other via differ-ent kinds of phase transitions. Conclusion The rich diversity of membrane lipids and their ability to adopt various crys-talline, gel and liquid-crystalline phases represent their most intriguing fea-tures involved in various cellular pro-cesses. The physiological importance of lipid diversity and mesomorphism stems from the possibility to fine-tune the biomembrane properties and modulate the lipid phase state in broad limits by altering the lipid chemical structure and composition.