Influence of Protein and Lipid Domains on the Structure, Fluidity and Phase Behavior of Lipid Bilayer Membranes
Author | : Margaret Ruth Horton |
Publisher | : |
Total Pages | : 148 |
Release | : 2006 |
ISBN-10 | : OCLC:166351561 |
ISBN-13 | : |
Rating | : 4/5 (61 Downloads) |
Book excerpt: (Cont.) At solid interfaces, we characterize the electron density profiles of protein-coated bilayers to determine how a water layer separates an immobile protein layer from the fluid lipid bilayer. Liquid-ordered lipid phases enriched in cholesterol and sphingomyelin can localize molecules in cell membranes and this lipid phase separation behavior may be influenced by proteins and molecules in the membrane. Caveolae are specialized liquid-ordered domains in the plasma membrane that are enriched in the protein caveolin-1. We demonstrate that caveolin-1 peptides influence the onset of lipid phase separation and bind phase-separated lipid bilayers in solution. On solid surfaces, the formation of liquid-ordered lipid phases is influenced by surface roughness; with reflectivity, we determine that lipid bilayers containing cholesterol and sphingomyelin thicken with increasing cholesterol content. The membrane receptor GM1 also thickens the lipid bilayer when it is incorporated into the bilayer upper leaflet. The diverse experimental platforms that we present are applicable to studying additional and more complex biological systems to elucidate the influence of lipid and protein domains on cell membrane structure, organization and fluidity.