Susan Gilbert's laboratory is engaged in detailed biochemical and kinetic analyses of the microtubule based molecular motors, Ncd and kinesin. Conventional kinesin is a neuronal ATPase that drives membranous organelle movements toward the synapse. In contrast, Drosophila Ncd is an essential motor for chromosome segregation during female meiosis and the early cleavages of the embryo. Ncd, unlike kinesin, moves one microtubule relative to another for the organization and maintenance of the spindle. Thus, kinesin and Ncd are model systems to define the mechanism that specifies the direction of movement along a microtubule, the unique characteristics of ATP turnover that result in very different cellular movements functionally, and the structural domains that generate the distinctive behavior of the kinesin and Ncd ATPases.
Yeast cells change the structure of microtubule arrays through different phases of the cell cycle.
Before anaphase, kar3 mutants have more microtubules than wild type. As anaphase begins that difference is lost. To verify experimentally the effects of the kar3 mutation, S. cerevisiae cells were arrested with hydroxyurea, released as a synchronous culture, and treated with antibodies to tubulin for microscopic imaging. Bill Saunders' laboratory is defining the role of the multiple molecular motors needed for the formation and function of the mitotic spindle using the power of genetic analysis in the yeast, Saccharomyces cerevisiae . A second, related area of interest in the Saunders lab is why mitosis occurs only once and at a specific time in the cell cycle.