PHE CRYSTAL-STRUCTURE OF DIMERIC KINESIN AND IMPLICATIONS FOR MICROTUBULE-DEPENDENT MOTILITY

The dimeric form of the kinesin motor and neck domain from rat brain w ith bound ADP has been solved by X-ray crystallography. The two heads of the dimer are connected via a coiled-coil alpha-helical interaction of their necks. They are broadly similar to one another; differences are most apparent in the head-neck junction and in a moderate reorient ation of the neck helices in order to adopt to the coiled-coil conform ation. The heads show a rotational symmetry (similar to 120 degrees) a bout an axis close to that of the coiled-coil. This arrangement is une xpected since it is not compatible with the microtubule lattice. In th is arrangement, the two heads of a kinesin dimer could not have equiva lent interactions with microtubules.