A novel peptide developed at the Universities of Bayreuth and Bristol is eminently suited for the targeted transport of molecules⁠—for example, of active substances and dyes⁠—into the cells of mammals. The peptide is characterized by a dual function: It can enter the cell from the outside and interact there with a partner peptide. The partner peptide must have previously been placed inside the cell exactly where the transported molecules are to take effect. The transport system presented in the journal Nature Chemical Biology exemplifies the promising potential of a de novo design of peptides and proteins.