Sorting of polyleucine peptides of different lengths in a membrane with a thickness gradient. The membrane consists of 4 types of phospholipids, and the thickness gradient is maintained with flat-bottom potentials. The peptides have sequences KKL_xKK, where x is 17,19,...,27. The peptides are coloured following "ROYGBIV*", i.e., red, orange, yellow, green, blue, indigo, violet from shortest to longest. The lysine caps help maintain the peptides in transmembrane orientation.In "Mismatch_multi", nine copies of peptides with 19 (top), 23 (middle), or 27 (bottom) leucines start from different locations in the same membrane and are spontaneously sorted by the thickness gradient. In "Mismatch_single", each membrane has a single peptide. The peptides start either from the intermediate (top), thin (middle), or thick (bottom) part of the membrane. The 7 simulations for the different peptides yet with the same initial position are overlaid. Note that the peptide with 29 leucines, starting from the thin membrane, never leaves this thin part. Otherwise, sorting takes place as expected in all the simulations.Trajectory frames every 100 ns ("single") or 200 ns ("multi") are shown from a 50-microsecond coarse-grained simulation with the Martini 2.1 force field. All details are available in the associated preprint at DOI:*) Boards of Canada – Roygbiv: https://www.youtube.com/watch?v=0nnqGDZnWhU