The cell membrane contains a large number of proteins, which perform a wide variety of functions. Some serve as transport channels, specifically guiding substances into the cell or carrying cellular products out of it. Others are receptors, which detect control signals and then trigger processes in the cell. These proteins are folded in complex three-dimensional structures, with the specific form essential for the protein function.

One question remains unanswered in many cases for researchers: How do the proteins manufactured by the ribosomes – the “factories” of the cells – in the cell interior reach their position within the membrane in the correct form and when did the processes become established over the course of evolution?