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Regular version of the site

Article

Optimality in self-organized molecular sorting

Physical Review Letters. 2021. Vol. 126. No. 8. P. 1-7.
Zamparo M., Valdembri D., Serini G., Kolokolov I., Lebedev V., Dall'Asta L., Gamba A.

We introduce a simple physical picture to explain the process of molecular sorting, whereby specific
proteins are concentrated and distilled into submicrometric lipid vesicles in eukaryotic cells. To this
purpose, we formulate a model based on the coupling of spontaneous molecular aggregation with vesicle
nucleation. Its implications are studied by means of a phenomenological theory describing the diffusion of
molecules toward multiple sorting centers that grow due to molecule absorption and are extracted when
they reach a sufficiently large size. The predictions of the theory are compared with numerical simulations
of a lattice-gas realization of the model and with experimental observations. The efficiency of the
distillation process is found to be optimal for intermediate aggregation rates, where the density of sorted
molecules is minimal and the process obeys simple scaling laws. Quantitative measures of endocytic
sorting performed in primary endothelial cells are compatible with the hypothesis that these optimal
conditions are realized in living cells.