High throughput screening of G-protein coupled receptors via flow cytometry

The molecular assemblies of signal transduction components, for example kinases and their target proteins or receptor-ligand complexes and intracellular signaling molecules, are critical for biological functions in cells. To better understand the interactions of these molecular assemblies and to screen for new pharmaceutics that could control and modulate these types of interactions, we have focused on developing high throughput approaches for the analysis of G-protein coupled receptors via flow cytometry. Flow cytometry offers a number of advantages including real-time collection of multicomponent data, and together with improvements in sample handling, the high throughput sampling rate is up to 100 samples per minute. For our targets, assemblies of solubilized GPCRs, a screening platform of a dextran bead has proven to be flexible, allowing different surface chemistries on the beads. The bead can be either ligand-labeled or have epitope-linked proteins attached to the bead surface, enabling several molecular assemblies to be constructed and analyzed. A major improvement with this system is that for screening ligands for GPCRs the underlying mechanism of action for these compounds can be investigated and incorporated into the definition of a 'hit'. Our current screening system is capable of simultaneously distinguishing GPCR agonists and antagonists.