Over a quarter of all proteins in a cell are found in the membrane, where they perform vital functions. To fulfill these roles, membrane proteins must be reliably transported from their site of production in the cell to their destination and correctly inserted into the target membrane. Researchers from the Heidelberg University Biochemistry Center (BZH) have succeeded in determining the three-dimensional structure of a molecular machine responsible for the correct placement of an important membrane protein family—the so-called "tail-anchored" membrane proteins, or TA proteins for short.