Interestingly, our continuum mechanics calculations showed that, when the impact of Ca 2+ is focused on a local surface area of a vesicle, a pearl chain extending toward the other side of the membrane can be generated (Fig. , S10, and S12). This is similar to recent observations that vesicle chain-growth from the GUV membrane can be maintained as long as there is a supply of membrane material and Ca 2+ , analogous to native secretory vesicles. This kind of remodeling can only be generated by an asymmetric effect in the two lealets of membranes, which may be related to membrane budding and fusion, morphology of ER exits, as well as the generation of interconnected vesicles. For example, dynamic membrane remodeling may be achieved by the interplay between lipids and Ca 2+ to initiate the formation of tubules. In contrast, when the impact of Ca 2+ is uniform on the membrane surface and Ca 2+ ions are added to the outside, the vesicle tends to remain spherical. When low-concentration Ca 2+ ions are uniformly added to the inside, vesicles tend to remain spherical as well. Intriguingly, the vesicle will become multi-spherical while more Ca 2+ ions are added to the inside (larger spontaneous curvature). This suggests that a signiicant reduction in stress within the inner lealet of membranes may facilitate vesicle ission, and could potentially aid cell division as well. A signiicant increase in stress within the outer lealet of membranes should have a similar effect, and so does the combination of the two. It should be noted though, we did not explicitly consider the asymmetry of the lipid composition of membranes in our continuum mechanics calculations. Moreover, the actual membrane compositions and environments are much more complex than the ideal cases studied here, so the eventual shape may be the result of many factors, including the distribution of proteins. Nonetheless, the distribution of Ca 2+ and negatively charged lipid molecules and their interplay may play important roles here.