title: Diffusion in phospholipid bilayer membranes: dual-leaflet dynamics and the roles of tracer-leaflet and inter-leaflet coupling.
abstract: A variety of observations-sometimes controversial-have been made in recent decades when attempting to elucidate the roles of interfacial slip on tracer diffusion in phospholipid membranes. Evans-Sackmann theory (1988) has furnished membrane viscosities and lubrication-film thicknesses for supported membranes from experimentally measured lateral diffusion coefficients. Similar to the Saffman and Delbrück model, which is the well-known counterpart for freely supported membranes, the bilayer is modelled as a single two-dimensional fluid. However, the Evans-Sackman model cannot interpret the mobilities of monotopic tracers, such as individual lipids or rigidly bound lipid assemblies; neither does it account for tracer-leaflet and inter-leaflet slip. To address these limitations, we solve the model of Wang and Hill, in which two leaflets of a bilayer membrane, a circular tracer and supports are coupled by interfacial friction, using phenomenological friction/slip coefficients. This furnishes an exact solution that can be readily adopted to interpret the mobilities of a variety of mosaic elements-including lipids, integral monotopic and polytopic proteins, and lipid rafts-in supported bilayer membranes.
authors.affiliation: Department of Chemical Engineering , McGill University , Montreal, Quebec, H3A 0C5, Canada.
authors.forename: Reghan J
authors.initials: RJ
authors.lastname: Hill
authors.affiliation: Department of Chemical Engineering , McGill University , Montreal, Quebec, H3A 0C5, Canada.
authors.forename: Chih-Ying
authors.initials: CY
authors.lastname: Wang
keywords: dual-leaflet membrane structure; lipid diffusion; membrane frictional coupling; membrane hydrodynamics; protein diffusion; self-diffusion