Biophysical Society Thematic Meeting | Ascona, Switzerland

Liposomes, Exosomes, and Virosomes: From Modeling Complex Membrane Processes to Medical Diagnostics and Drug Delivery

Friday Speaker Abstracts

Colocalization of Lipid Domains Across the Two Faces of a Membrane Sarah L. Keller , Matthew C. Blosser.

The wide diversity of lipid and protein types within a cell’s plasma membrane can leave researchers both enthralled by the membrane’s richness and overwhelmed by the membrane’s complexity. Our laboratory investigates giant unilamellar vesicles as a model of plasma membranes in cells. We find that many physical behaviors reported in complex plasma membranes occur in our model, protein-free membranes. For example, the distribution of lipids on one face of the membrane strongly affects the distribution on the other. In other words, the two opposing leaflets of the membrane are strongly coupled, even when no proteins are present. More recently, we have measured the strength of this coupling by shearing membranes within a microfluidic device, which causes the upper leaflet of the membrane to slide over the lower leaflet, moving domains out of registry. We convert our experimental results into an energy penalty per unit area for misregistered domains. This value sets a lower limit on the size of sub- micron domains in each leaflet that should align across the two faces of a membrane due to coupling of the lipids alone. Alignment of smaller domains in each leaflet would require stronger coupling due to, for instance, transmembrane proteins.

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