Scientists led by David Baker’s lab at the University of Washington developed a generalizable molecular switch design that precisely modulates protein-protein binding kinetics, increasing dissociation rates up to 6,000-fold. This innovation facilitates safer, on-demand drug activation and deactivation, with application demonstrated on interleukin-2 immune cytokines. This advance in protein design refines control over timing of biological interactions, crucial for reducing side effects and improving treatment specificity in biopharmaceuticals.