ncd Background Information The microtubule cytoskeleton functions as a framework for a wide variety of intracellular movements (1). Microtubule motors bind to and move unidirectionally on microtubules, and may generate the force required for spindle assembly and maintenance, attachment of the chromosomes to the spindle, and movement of chromosomes toward opposite poles (2). These movements are powered by members of the kinesin superfamily (1). In Drosophila, non-claret disjunctional (ncd) is an unusual member of the kinesin family that moves opposite to kinesin, toward the microtubule minus end (2–4). ncd acts to maintain centrosome integrity and attachment to nuclei, contributes to midbody stability, and helps to prevent chromosome loss during the early mitotic divisions (2). It is also required for chromosome segregation during meiosis in oocytes (2). The conserved motor domain (340 amino acids long) of ncd is globular in structure and is at the carboxy terminus (5). This region encompasses an ATP and microtubule binding site and is sufficient for force generation and microtubule motor activity (1).
