Phosphorylation of KLP10A at S573 alters its interactions with the MT lattice. (a) Electron micrographs of MTs incubated with either KLP10A S573A (top) or S573E (bottom) neck/motor constructs. (b) Three independent protein preparations for each construct were analyzed, and only MTs with KLP10A bound were included in the measurements. n = 352 (wt), 359 (S573A), and 393 (S573E). (c, left) Overlay of the structures of an unphospho- and phospho-KLP10A motor domain obtained from molecular dynamics simulations by minimizing the root mean square difference between the two structures. Regions of the molecule that remain unchanged are shown in light gray, whereas those that undergo significant conformational changes are shown in color (unphospho, red; phospho, green). The phosphorylation site is shown in blue. (right) Overlay of the structures of a tubulin heterodimer in complex with the unphospho- or phospho-KLP10A motor domain. We note that the core regions of the two KLP10A do not overlay very well because of the difference in their relative positions to β-tubulin. Bar, 125 nm.