Subunits of TpH acquire four different conformations. (a) The ten protomers of TpH can be assigned to four conformers based on the position and orientation of FU-d*s and FU-gs. Molecular models are shown as ribbon diagrams. FU-d* and FU-g are shown in yellow and cyan, respectively. The wall region is colored gray. (b) Classification of the ten protomers in four conformers (c and d) Comparison of FU-d*s and FU-gs between conformer 1 and 3 (c) and between conformer 2 and 4 (d). FU-d* (yellow) and FU-g (cyan) of conformer 1 (left) and 3 (right), after aligning the wall regions, are shown (c). Vectors in the middle indicate the direction of motion between the collar FUs from conformer 1 to conformer 3. Those between conformer 2 (left) and 4 (right) are shown in (d).