Amino acids are essential components of all living cells serving as building blocks of proteins, as energy source, and as precursors of metabolites and signaling molecules. Amino acid transporters are membrane proteins that mediate the transfer of amino acids between cellular compartments, between different cells and between organs. Absence, overexpression or malfunctioning of certain amino acid transporters can be associated with human diseases. For example, cancer cells have reprogramed their energy metabolism to efficiently support tumor growth and metastasis formation. This includes alterations of amino acid catabolism and upregulation of amino acid transporters that lead to the activation of crucial signalling pathways, e.g. mTOR, linking growth signals to nutrient availability. The research project investigates in vitro and in vivo whether a specific amino acid transporter of the SLC7 family can serve as a suitable drug target or drug delivery system for cancer chemotherapeutic strategies. Furthermore, the project aims at elucidating the working mechanisms of selected SLC7 family members at the molecular level by functional and structural studies of human SLC7 family members and prokaryotic homologues.