Difference H-bond graphs illustrate the conserved and unique H-bonds of Hc KCR1 and Hc CCR. Gray dots (graph nodes) and lines (graph edges) indicate amino acid residues and their connections which are conserved (present) in both structures, whereas blue nodes and edges show amino acid residues and H-bonds which are unique to each structure. Red dots (nodes) are water molecules determined in the cryo-EM structures. The H-bond graphs were computed using Bridge 21 and C-Graphs 22 programs with a distance criterion of 4 A between the H-bond donor and acceptor hetero-atoms. Bold edges indicate distances 3.5 A. The H-bond graph is projected to a two-dimensional plane, where the vertical axis corresponds to the coordinates of the C atoms of the amino acid residues along the membrane normal (z coordinate), and the horizontal axis shows the Principal Component Analysis (PCA) projection along the membrane plane (xy coordinates). Difference H-bond graph of Hc CCR relative to the conserved H-bond graph.
