Uncovering biases in high throughput screens of G-protein coupled receptors

The ability of high throughput membrane binding assays to detect ligands fo r G-protein coupled receptors was examined using mathematical models. Membr ane assay models were developed using the extended ternary complex model (S amama et nl., 1993) as a basis. Ligand binding to whole cells was modeled b y adding a G-protein activation step. Results show that inverse agonists bi nd more slowly and with a lower affinity to receptors in the membrane bindi ng assay than to receptors in whole cells, causing the membrane assay to mi ss pharmaceutically important inverse agonists. Assay modifications to allo w detection of inverse agonists are discussed. Finally, kinetic binding dat a are shown to provide information about ligand efficacy. This work demonst rates the utility of mathematical modeling in detecting biases in drug-scre ening assay, and also in suggesting techniques to correct those biases. (C) 2001 Academic Press.