Professor DeLozanne is interested in defining the molecular basis of the lysosomal disorder known as the Chediak-Higashi Syndrome. This disease is caused by mutations in a very large gene and result in the loss of a large protein known as Lyst. The size and low abundance of this protein have impaired the detailed analysis of its function and how its absence leads to the dysfunction of lysosomes in CHS patients. A simple model system has been established to study the molecular function of Lyst and closely related proteins in the organism Dictyostelium discoideum. It has been shown that the loss of a similar protein in this organism results in the same lysosomal defect. Currently the wide array of molecular tools available in this model system is being studied to dissect the function of Lyst-related proteins. The hope is to use this as a starting point to better understand the human disease and design potential therapies. Also of interest is understanding how eukaryotic cells accomplish the last stage of the cell cycle: cytokinesis. Several proteins important for cytokinesis have been established and have generated knockout mutants lacking these proteins. The phenotypes of these mutants are then analyzed using a variety of cell biological techniques including imaging of GFP-labeled proteins. One of these proteins called LvsA plays a role in membrane traffic, while another called INCENP binds to chromosomes and microtubules. The analysis of proteins like these will help delineate the molecular mechanisms involved in cell division.