Fig. 3. Kinesin-13 motor domain structure. (A) 3D ribbon structure of the Plasmodium falciparum kinesin-13 motor core (Shipley et al., 2004). Orthogonal views are shown in which the `front' view is as if the MT surface were behind the motor domain; the top of the motor domain would point towards the MT plus end. The -helices are shown in dark blue and are individually labelled and the ß-sheets are shown in light blue. The pdb code for this structure is 1RY6. (B) Schematic of the interaction between the MT lattice and a kinesin motor domain. (C) 3D ribbon structure of the Homo sapiens MCAK neck+motor construct (Ogawa et al., 2004). The visible portion of the neck region is shown in orange but only represents about a third of the total neck sequence (see alignment in Fig. 2B). The left-hand view shows the front of the motor and the right-hand view shows a 90° rotation, as if viewing the motor-MT interaction from the side. The green line indicates where the MT surface would be and shows that the curvature of the motor domain would match the more curved surface of flexible tubulin dimers at MT ends. The pdb code for this structure is 1V8K. Atomic structures were displayed using PyMOL (http://www.pymol.org).