Quantitative analysis of metabotropic glutamate receptor activation and modulation

The principal excitatory transmitter in the brain is glutamate and dysfunction of glutamate signaling is known to be a key factor in severe neurological conditions such as glioma, fragile X syndrome, epilepsy, anxiety, depression, schizophrenia. Metabotropic glutamate receptors (mGluRs) are critical conductors of glutamate signaling in the brain and due to their central role they are among the most promising drug targets for the neurological disorders. Extraordinary advances in protein engineering and functional, structural and computational methods in the past twenty years have provided insights into the molecular basis for their activation and interaction with G proteins and β-arrestin. However, a general model of how ligands change the shape of mGluRs and how this conformational change is relayed across the membrane to activate specific signaling pathways is poorly understood. In this research we will develop a novel technology that will allow us to watch a single mGluR protein while functioning in physiological conditions, in real time. This technology will allow us to systematically capture and quantify sequential steps of mGluR signaling from ligand binding to the receptor activation. We will employ our approach to study the conformational dynamics of selected mGluRs of biological and medical significance (mGluR1 and 2). Once accomplished, the proposed research could provide a critical step towards rational design of efficient GPCR drugs with fewer undesirable side effects. Furthermore, these studies will provide a general roadmap for quantitative high resolution structure-function studies of full-length mammalian membrane proteins.