Microtubule-based motor function in mitosis

Microtubule-based motors are essential both for the proper assembly of the mitotic spindle and for chromosome segregation. Mitotic motors in the yeast Saccharomyces cerevisiae exhibit either overlapping or opposing activities in order to achieve proper spindle function, whereas the analysis of motor s using vertebrate cytoplasmic extracts has revealed less functional redund ancy. In several systems, biochemical, genetic and two-hybrid approaches ha ve been used both to identify associated nonmotor proteins and to address t he molecular mechanisms behind kinetochore movements during chromosome alig nment and segregation.