Biological membranes are intimately associated with the evolution of life, providing a barrier to or within the cell that allows for compartmentalization and structure formation as well as concentration of molecules. However, any living cell has to communicate via this barrier with its environment and, therefore, membranes are equipped with a multitude of membrane proteins that are required for uptake and export of molecules, and for communication across this barrier (sensing of stimuli and signal transduction to intracellular targets). This pivotal role of membrane proteins is exemplified in genomes from all kingdoms of life, in which 25-30% of the genetic information encodes for membrane proteins. Despite their importance for the physiology of cells, a precise understanding of membrane proteins and processes are only rarely available. In particular, transport processes and information transfer are often not well resolved, even though they are of paramount interest from a biomedical standpoint of view as reflected by the fact that roughly 60% of the currently used medical drugs target transmembrane processes. This discrepancy between our knowledge and the importance of transmembrane processes will ensure that this research area will stay in the focus both of academic research as well as the pharmaceutical industry for years to come.