Fig. 1: Comparison of GMPCPP- and GDP-tubulin heterodimer structures in solution.

a Cα-trace superimposition of the two tubulin heterodimer models between GMPCPP (cornflower blue) and GDP-1 (hot pink) state, aligned on the α-tubulin (same for b–d). b Cα-atoms-RMSD between the two models shown in a, with deviations colored from blue to red. The chain-trace being displayed corresponds to the GMPCPP-tubulin model. Displacement vectors of Cα-chain of H1-S2 and H2-S3 loops in β-tubulin are represented by heavy lines in the inset. The vector >1 Å is colored in red and <1 Å is colored in blue (same for d). c Cα-trace superimposition of the two tubulin heterodimers between GMPCPP (cornflower blue) and GDP-2 state (yellow). d Cα-atoms-RMSD between the two models shown in c. The inset shows the displacement vectors of H1-S2 and H2-S3 loops. e–g The density of cryo-EM maps (mesh) and corresponding models of H2-S3 loop and M-loop. β-tubulin is shown in the left panel and α-tubulin in the right panel. e GMPCPP state. f GDP-1 state. g GDP-2 state. Electron densities are contoured at 3.06 σ.