Impact of nanoscale hindrances on the relationship between lipid packing and diffusion in model membranes

Abstract

Membrane models have allowed for precise study of the plasma membranes biophysical properties, helping to unravel both structural and dynamic motifs within cell biology. Free standing and supported bilayer systems are popular models to reconstitute the membrane related processes. Although it is well-known that each have their advantages and limitations, comprehensive comparison of their biophysical properties is still lacking. Here, we compare the diffusion and lipid packing in giant unilamellar vesicles, planar and spherical supported membranes and cell-derived giant plasma membrane vesicles. We apply florescence correlation spectroscopy, spectral imaging and super-resolution STED-FCS to study the diffusivity, lipid packing and nanoscale architecture of these membrane systems, respectively. Our data show that lipid packing and diffusivity is tightly correlated in free-standing bilayers. However, nanoscale interactions in the supported bilayers cause deviation from this correlation. This data is essential to develop accurate theoretical models of the plasma membrane and will serve as a guideline for suitable model selection in future studies to reconstitute biological processes.