Extended Data Fig. 9: Analysis of microtubule curvature.

The interprotofilament angle is defined as the relative rotation (in conjugation with necessary translation) from a tubulin heterodimer on one protofilament to the neighboring tubulin heterodimer on a second protofilament. The red dashed line at 27.7° is the theoretical interprotofilament angle for a perfectly symmetric 13-protofilament microtubule (360° divided by 13). The seam locations for each microtubule are indicated with asterisks. Note for in vitro assembled GDP microtubule, the largest interprotofilament angle occurs at the seam as previously reported²³.