Back calculated structures by distance geometry.

<p>α and β are in warm and cool colors, respectively. Quaternary T state is in light pink and light blue. R is in median red and median blue. R2 is in dark red and dark blue. T_High is in white. A ribbon model represents one dimer in background. The opposite dimer is then in stick model in foreground. T and R are in thick stick models. T_High and R2 are in thin stick models. All structures are aligned by least-squares fitting of the invariant framework of α1β1 identified by the rmsd matrix (Figure S11a). <b>a</b>. Five structures are superimposed: Ttttt or 01, Trttt or 11, Trrtt or 21, Rrrrt or 31, and Rrrrr or 41. α1β1 is in background and α2β2 is in foreground. Movie S4 shows these structures in motion. <b>b</b>. Same as <b>a</b> except that α2β2 is in background and α1β1 is in foreground. The relation of viewpoints is indicated by a flip of the page. Movie S5 shows these structures in motion. <b>c</b>. Same view as in <b>a</b>. Four consensus structures are superimposed: T_High, T, R, and R2. Some motions of α2β2 are also indicated by the inserted vector diagrams. The lengths of vectors are twice as long as the observed motions.