The binding site of GlyR comprises a diverse range of residues which consistently interact with glycine mainly through hydrogen bonds (including water-bridged ones) and cation-π interactions. The occurrence (accounting whether a residue interact with glycine), average number (including also the possibility of multiple bonds with the same residue) and corresponding standard deviation of hydrogen bonds, water-bridged hydrogen bonds and cation-π interactions are reported in Tables 1, 2 and 3 respectively. A typical bonding pattern with key residues is shown in Figure .