We are now on the verge of viewing effector molecules and other regulatory sites as therapeutic targets for the amelioration of human and animal disease. The recognition, for example, that mutant proteins are frequently misrouted molecules, rather than functionally defective ones, changes our approach to "inborn errors of metabolism" and offers new approaches for pharmacological discovery, based on rescue of receptors, ion channels and enzymes with pharmacoperones. Ion channels, regulators of G-protein signaling and enzymes engaged in regulation, now present opportunities for drug development.The state of our art also benefits by the availability of superior tools that allow measurement of interactions and afford unprecedented insight into the biomolecular interactions that present novel approaches to drug design.