G-protein-coupled receptors (GPCR) are membrane receptors. GPCR can sense stimuli such as light, odorants, hormones, mechanical impulses and neurotransmitter. These stimuli are transduced into cellular signaling cascades. GPCR are an important pharmacological target. Of the drugs with known molecular target every third affects one of the about 800 human GPCRs (~ 4% of all genes).
We are investigating ligand-induced conformational dynamics of GPCR on the example of the metabotropic glutamate receptor mGluR1. mGluR1 senses the neurotransmitter glutamate and influences synaptic long-term potentiation and ultimately learning.
mGluR1 is a homo-dimer. We follow the ligand induced conformational rearrangements between the subunits with FRET, using CFP and YFP inserted in the two subunits as FRET partners. Time resolution is optimized by using electrophysiological methods: solutions in front of small membrane fragments (outside-out patches) are changed with a piezo-driven application system. With this we achieve sub-ms time resolution, at least an order of magnitude faster than good cell-biological assays.