Optical techniques to analyze real-time activation and signaling of G-protein-coupled receptors.
The activation of G-protein-coupled receptors (GPCRs) is traditionally measured either by monitoring downstream physiological events or by membrane-based biochemical assays. Neither of these approaches permits detailed kinetic or spatial analysis of receptor activation and signaling. Recently, several optical techniques have been developed to monitor receptor activation either by using purified reconstituted GPCRs or by observing GPCRs, G proteins and second messengers in intact cells. These techniques are providing, literally, new views on both the mechanistic basis of the signaling process and the kinetic and spatial properties of GPCR-mediated signals. They suggest that agonists can activate GPCRs within milliseconds, that different compounds can induce distinct active conformations of GPCRs, that G-protein activation is the rate-limiting step in GPCR signaling, and that cellular signals can be temporally and spatially confined. They are also raising controversial issues, such as whether or not receptors and G proteins are pre-coupled and whether G proteins dissociate during activation.
Lohse
Martin J
MJ
Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany. lohse@toxi.uni-wuerzburg.de
Nikolaev
Viacheslav O
VO
Hein
Peter
P
Hoffmann
Carsten
C
Vilardaga
Jean-Pierre
JP
Bünemann
Moritz
M
D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002478:Cells, Cultured; D031541:Fluorescence Resonance Energy Transfer; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D043562:Receptors, G-Protein-Coupled / Q000819:agonists / Q000378:metabolism*; D015398:Signal Transduction
D008164:Luminescent Proteins; D043562:Receptors, G-Protein-Coupled