Structural stability of claudin-15 strands. (a and b) Root-mean-square deviation (RMSD) values of the protein backbone and transmembrane (TM) helices backbone with respect to the initial structure throughout the simulation trajectory of (a) all-atom and (b) hybrid model. Average of RMSD values of the 36 monomers are shown in bold lines. (c) Secondary structure content of claudin-15 monomers averaged over 36 monomers and the trajectory time in all-atom (250 ns) and hybrid (1 µs) models of claudin-15 strands. (d) RMSD values for the backbone of the tetrameric unit of claudin channels with respect to their initial structure and the average over eight channels. (e) The tetrameric unit of the claudin channel forming an ion conduction pore in paracellular space. Horizontal bars represent the boundaries of the membrane of two adjoining cells.