Protein–Protein Communication Mediated by an Antibody‐Responsive DNA Nanodevice**

We report here the rational design and optimization of an antibody-responsive, DNA-based device that enables communication between pairs of otherwise non-interacting proteins. The device is designed to recognize and bind a specific antibody and, in response, undergo a conformational change that leads to the release of a DNA strand, termed the "translator," that regulates the activity of a downstream target protein. As proof of principle, we demonstrate antibody-induced control of the proteins thrombin and Taq DNA polymerase. The resulting strategy is versatile and, in principle, can be easily adapted to control protein-protein communication in artificial regulatory networks.