Inside cells, communication between the nucleus, which harbors our precious genetic material, and the cytoplasm is mediated by the constant exchange of thousands of signaling molecules and proteins. Until now, it was unknown how this protein traffic can be so fast and yet precise enough to prevent the passage of unwanted molecules. Through a combination of computer simulations and various experimental techniques, researchers have now solved this puzzle: A very flexible and disordered protein can bind to its receptor within billionths of a second.