Fig. 10

The selectivity filter of HsAQP8 remains AtTIP2;1-like during the MD simulation. The selectivity filter of each of the four monomers of the tetramer in the last frame of the 3 ns simulation, the monomers are aligned to facilitate comparisons. The residues of the selectivity filter, H66 (H2^P), F139 (LC^P), I192 (H5^P), G201 (LE^P), R207 (HE^P) as well as A137 in loop C are shown in stick representation together with the carbonyl oxygens of G200 and C202 lining the pore. R207 is stabilized in an AtTIP2;1-like position via hydrogen bonds (dashed lines) to H66 and to A137 of loop C via a water molecule, which has a variable position and is exchanged occasionally (Additional file 5: Movie S1). The orientation of the carbonyl of G201 (LE^P) mainly points to the centre of the pore. The side pore remains more or less water filled during the simulation; the blue mesh marks the surface of water molecules in the last frame