Figure 15. Segmented subtomogram averaging.

(A) Segment 1. (B) Segment 2. (C) Segment 3. (D) Segment 4. Views turned by 180° around the Y-axis are displayed in (A–D). The kinesin motor domain densities in the three front protofilaments of segments (1–3) are shifted longitudinally by ~49.2 Å indicating that the underlying αβ-tubulin molecules share heterotypic interactions of the A-type. Conversely, they are shifted longitudinally by ~9.2 Å in segment 4 indicating that the underlying αβ-tubulin molecules share homotypic interactions of the B-type.