Tubulin ribbon diagram

Figure 7-33 Stereoscopic ribbon diagram of the tubulin dimer with a-tubulin with bound GTP at the top and P-tubulin with bound GDP at the bottom. The p-tubulin subunit also contains a bound molecule of taxotere (see Box 7-D) which is labeled TAX. This model is based upon electron crystallography of zinc-induced tubulin sheets at 0.37-nm resolution and is thought to approximate closely the packing of the tubulin monomers in microtubules.315 The arrow at the left points toward the plus end of the microtubule. Courtesy of Kenneth H. Downing.

Fig. 4. Atomic models of tubulin in straight and curved conformations. Ribbon diagrams similar to that in Figure 3, with the same color scheme. (A and B) Outside and side views of the straight heterodimer (Lowe et al., 2001). (C) Crystal structure of the...

Fig. 5. 3D EM shows how kinesin and tau bind to microtubules. (A) Reconstruction of a microtubule decorated with kinesin heads (ochre). One kinesin head binds per afi-tubulin heterodimer (grey) and, due to its asymmetric form, can be used to distinguish between the subunits. (B) Inside view of a microtubule that was coassembled with gold-labeled tau and decorated with kinesin heads. The kinesin heads can be seen on the outside through the holes between the protofilaments. The labeled repeat motif of tau binds to the inside face of microtubule. The averaged nanogold density (yellow), which is attached to a repeat motif of tau through a linker, can only be seen near the Taxol binding site of -tubulin, but not on the a subunit (Kar et al, 2003a). The ribbon diagram of the refined zinc-sheet structure is also shown for reference (see Figure 3).

Fig. 2 Ribbon diagram of the structure of the a/p-tubulin dimer in 2D zinc-induced sheets (PDB entry 1TUB). The p monomer is on top. Some elements involved in PTX binding and lateral contacts are colored M loop in green, S9-S10 loop in blue, helix H7 in yellow, and helix H3 in orange. Small-molecule ligands are represented as sticks PTX in red, GDP and GTP in magenta. The a-tubulin S9-S10 loop occupies a position equivalent to that of PTX in P-tubulin...

Fig. 15 Ribbon diagrams of tubulin in complex with MT-stabilizing drugs as determined by EC or NMR. Left PTX/tubulin determined by EC (PDB entry 1JFF [83]). Center EpoA/tubulin determined by EC (PDB entry 1TVK [26]). Right EpoA/tubulin determined by solution NMR [76]. Drug molecules are represented as stick models (C red, O blue, N green, S yellow). Some secondary structure elements of tubulin are colored helix H7 (yellow), M loop (green), S9-S10 loop (blue). The side chain of His227 is depicted as cyan sticks...

Figure 1. Ribbon diagram of tubulin and a schematic representation of the microtubule. Figure reproduced with permission from Werbovetz KA. Tubulin as an antiprotozoal drug target. Mini Rev Med Chem 2002 2 519-529. 2005 Bentham Science Publishers Ltd.

Fig. 4 Diagram of the crystal structure of the T2R complex showing the binding sites of MT-destabilizing drugs (PDB entry 1Z2B) [13]. Protein subunits are represented as ribbons. RB3-SLD is colored orange, a-tubulin is purple, and p-tubulin is green. Small-molecule ligands are represented as spheres (vinblastine orange, colchicine red, GTP yellow, and GDP magenta). Colchicine binds to the p-subunit at the intradimer interface. Vinblastine binds at the interdimer interface...

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