Figure 4.

Comparison of the local subunit packing of the three different helical symmetries. (A) Local lattices of the Lt-, L-, and R-type are superimposed with the filament axis vertical. (B) Lattices are tilted so that the lattice lines representing the protofilaments (the 11-start) are superimposed. Lines and circles are colored red for the Lt-type, blue for the L-type, and black for the R-type. The lattices are drawn on the cylindrical surface at the radius of 45 Å, which corresponds to the radial position of the center of the outer-tube structure shown in Fig. 3. The lattice parameters were calculated from the helical symmetries (Table 1), which were obtained from the layer-line spacings in the x-ray fiber diffraction patterns (the diffraction pattern of the Lt-type is in Fig. 1G; data not shown for the L- and R-type). (Bar = 20 Å.)