Abstract
Cytokinesis is the final stage of cell division, through which cellular constituents of mother cells are partitioned into two daughter cells resulting in the increase in cell number. In animal and fungal cells cytokinesis is mediated by an actomyosin contractile ring, which is attached to the overlying cell membrane. Contraction of this ring after chromosome segregation physically severs the mother cell into two daughters. Here we describe methods for the isolation and partial purification of the actomyosin ring from the fission yeast Schizosaccharomyces pombe and the budding yeast Saccharomyces cerevisiae, which can serve as in vitro systems to facilitate biochemical and ultrastructural analysis of cytokinesis in these genetically tractable model systems.