GENETIC-ANALYSIS OF THE MITOTIC SPINDLE

Much of our understanding of the molecular basis of mitotic spindle fu nction has been achieved within the past decade. Studies utilizing gen etically tractable organisms have made important contributions to this field and these studies form the basis of this review. We focus upon three areas of spindle research: spindle poles, centromeres, and spind le motors. The structure and duplication mechanisms of spindle poles a re considered as well as their roles in organizing spindle microtubule s. Centromeres vary considerably in their size and complexity. We desc ribe recent progress in our understanding of the relatively simple cen tromeres of the yeast Saccharomyces cerevisiae and the complex centrom eres that are more typical of eukaryotic cells. Microtubule-based moto r proteins that generate the characteristic spindle movements have bee n identified in recent years and can be grouped into families defined by conserved primary sequence and mitotic function.