Ribbon representation of FhuA Δ1-159 Ext. Model is shown in side and top view. Lys residues are shown in VdW representation; side view: O - outer part, M - intermembrane part, P - periplasmatic part; top view: only Lys present in the channel (4) are shown. Graphical representations obtained by VMD (Visual Molecular Dynamics program ver. 1.6, http://www.ks.uiuc.edu/Research/vmd/).