Figure 4

Superposed secondary structure elements. a) Ribbon representation of the conserved SSEs surrounding the ATP/PP binding site: four beta filaments and an alpha-helix. The 1b0uA chain is shown in blue, the 1kklA chain in orange. The four beta filaments form a beta-sheet, whose second filament corresponds in both structures to the ploop preceding sequence. The helix corresponds to the sequence immediately following the ploop structure. The superposition of the two beta-sheets shows the two internal filaments displaying the same orientation in space (in both structures, the filaments point up in an N to C direction). The two external filaments point in opposite directions in the two structures. The first filament on the left side of the picture corresponds to the sequence surrounding the catalytic histidine; the fourth filament on the right is not involved in any known specific functional region. b) Topology of the superposition. A simplified view of the superposed structure is shown with the same colors used in Figure 4a. Beta filaments are represented as arrows, pointing from N to C; the helices are represented as cylinders. The protein stretches joining the secondary structure elements are depicted with no relation to their real length.