The basic mechanism proposed in PACE by R.Serra and colleagues, is based simply on the existence of a large volume difference inside and outside a vesicle.
So that processes in which molecules are produced via membrane bound catalysis and released into the surrounding fluid, even with a symmetric release to either side, can result in a major build of concentration inside a vesicle. We simulated such a mechanism of amphiphile (lipid L) creation from a resource (precursor P),
that in turn is produced everywhere in solution at a very slow rate. The reaction kinetics are then of the form shown. The radial distribution of lipids (red) and of precursors (green) as a function of time in the figure, shows the establishment of a steady state concentrated resource inside and near the vesicle. An image of a single time snapshot from this mprDPD simulation is shown in the side bar (water is not shown, and lipids are yellow, precursors red, in this image).