Significance Allostery is a process in which a signal sensed upon ligand-binding at a distal site is transduced to the effector site, allowing for regulation of the activity of the latter. The propagation of an allosteric signal is a nonequilibrium process, but neither the nature of the signal is known on a molecular level (e.g., whether it is structural or dynamical properties that change) nor its speed. The real-time observation of such a signal requires the design of protein systems, in which one can synchronize ligand (un)binding events. Such a design is presented here, allowing us to investigate its allosteric transition in unprecedented detail.