Dynamic sorting of lipids and proteins in membrane tubes with a moving phase boundary

摘要: Cellular organelle membranes maintain their integrity, global shape, and composition despite vigorous exchange among compartments of lipids proteins during trafficking signaling. Organelle homeostasis involves dynamic molecular sorting mechanisms that are far from being understood. In contrast, equilibrium thermodynamics membrane mixing sorting, particularly the phase behavior binary ternary model mixtures its coupling to mechanics, is relatively well characterized. Elucidating continuous turnover live cell membranes, however, calls for experimental theoretical models enabling manipulation investigation directional mass transport. Here we introduce phenomenon curvature-induced domain nucleation growth in with fluid coexistence. Membrane domains were consistently observed nucleate precisely at junction between a strongly curved cylindrical (tube) pipette-aspirated giant unilamellar vesicle. This geometry mimics intracellular compartments, because they often show tubular-vesicular regions. Nucleated tube necks present diffusion barriers transport proteins. We find curvature-nucleated grow characteristic parabolic time dependence curvature-dependent. derive an analytical reflects dynamics. Numerically calculated shapes furthermore allow us elucidate mechanical details underlying curvature-dependent directed lipid Our observations suggest novel principle may contribute protein trafficking.