Our research is in the area of cell surface receptors and their coupled signal transduction processes, which involves how cells respond to chemical mediators in their external environment. The model systems under study mainly focus on the beta-adrenergic and adenosine receptors and their subtypes, which mediate a number of important cellular and physiological responses and are targets for drug development. Specific interests include the mechanisms of receptor activation and mechanisms of interaction between receptors (cross-talk), which affect intracellular mediators differently. The design and synthesis of novel receptor ligands are also of interest and include structure-activity relationships for partial agonists, enhanced receptor subtype selectivity, and bifunctional ligands, where a single chemical entity can affect the activity of more than one receptor. Irreversible receptor ligands are also used to study the relationship between receptor occupancy and response (coupling efficiency) and the mechanisms for how this relationship changes during health and disease.