Figure 6.

Water-inaccessible voids located in microtubules. A spherical probe for H₂O with a radius of 1.4 Å was used for the calculations. (A) Three-dimensional structure of the guanosine-5’-[(α,β)-methyleno]triphosphate (GMPCPP)-bound microtubule showing the voids (gray) located in the α- and β-subunits, as well as the homotypic lateral contacts (blue) between the protofilaments. (B) Packing defects (voids) formed at the inter- and intradimer contact sites along the protofilament. The images were prepared and modified with UCSF Chimera v1.11.2 using PDB: 3J6E. (C) Comparison of the total volumes of voids/packing defects within the subunits and at the contact sites of microtubules for the distinct chemical states produced by binding to GMPCPP, GDP, or taxol. To see this figure in color, go online.