Charakterisierung der apikalen Transportwege und beteiligten Proteinkomponenten in polaren Epithelzellen

The plasma membrane of polarized epithelial cells is divided into two separate membrane compartments, the apical and the basolateral domain. Based on their functional specialization the domains are composed of different proteins and lipids. This is maintained by an intracellular machinery that directs newly synthesized material into the correct target membrane. Polypeptides from the apical membrane domain of epithelial cells classically reach their destination by a sequential passage from the ER through the Golgi to the TGN, from where they are sorted into apical transport vesicles. Dependent on their lipid raft affinity apical proteins are segregated into distinct vesicle populations. The investigations are focused on the transport and sorting machinery in apical transport. For this, two model proteins were used, the lipid raft-associated SI and the non-raft-associated LPH. Biochemical approaches and fluorescence microscopy studies identified that SI and LPH traverse endosomal compartments before entering the apical membrane. Furthermore the role of the lectin galectin-3 in LAV and the role of the kinase ALPK-1 for SAV were reported.