Dynamic Sorting of Lipids and Proteins in Multicomponent Membranes

Dynamic sorting of lipids and proteins in cellular membranes plays a critical role in establishing and maintaining distinct compositions in various organelles. Recent experiments found that the lipid sorting in a membrane tube highly depends on the pulling speed at the tip. However, the mechanism of this velocity dependence has not yet been revealed. In this Letter, we found that when a membrane is deformed rapidly, the lipid flow induced by fast membrane shape change will significantly affect the sorting results. The competition between the curvature-driven lipid sorting and the pulling-induced lipid flow leads to novel behaviors. When a membrane tube is pulled out from a liquid ordered (L-o) domain at a constant speed, slow pulling leads to the formation of a liquid disordered (L-d) tube, while fast pulling results in a L-o tube. Interestingly, in a membrane tube pulled at an intermediate speed, alternate L-d and L-o domains appear in the tube. The sorting dynamics and the corresponding pulling force were systematically studied. The results of this study could lead to a better understanding of the dynamic sorting and traffic of lipids and proteins in living cells.