50 / 120
Liposomes, Exosomes, and Virosomes: From Modeling Complex
Membrane Processes to Medical Diagnostics and Drug Delivery
Friday Speaker Abstracts
45
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.