All eukaryotic cells have a complex three dimensional organization.
As a model system we are studying a simple cell type, epithelialcells, which form a layer lining a surface or cavity. These two plasma membrane domainshave completely different protein compositions. To understandcell polarity we are studying how membrane proteins are sent tothe correct surface. Recent evidence suggests that the principlesunderlying these polarized sorting process apply generally toother cell types, such as neurons. This protein makes twopolarized sorting decisions.