Molecular analysis of racE function in Dictyostelium

Dictyostelium has long proven to be a valuable system for studying various aspects of the cytoskeleton and cell motility. In this review we describe the isolation of a novel gene, racE, and how we have used multiple approaches to learn how the product of this gene is involved in cytokinesis. The racEgene was isolated in a screen designed to identify genes specifically required for cytokinesis. The use of GFP fusion proteins, coupled with mutational analysis, allowed us to determine that racE exerts its function at the plasma membrane throughout the entire cell cycle. Measurements of cortical tension and observations of live cells in suspension culture revealed that racE is involved in the regulation of cortical tension and actin organization at the cortex. We postulate that in the absence of proper cortical tension, cytokinesis cannot proceed normally.