tRNA recognition sites (distal b-barrel, green; and acceptor binding region, yellow) and hinge-bending region (red) of GlnRS revealed by the slowest mode shapes displayed in Figure 9 (see legend to Figure 9). These region shown in red acts as a hinge in monitoring the collective motion (relevant to catalytic function) of the synthetase. The ATP bound in the active site cleft is shown in magenta.

"Vibrational dynamics of transfer RNAs. Comparison of the free and enzyme-bound forms"
I. Bahar, R. L. Jernigan, J. Mol. Biol. 281, 871-884, 1998