Nature Neuroscience5, 1163 - 1168 (2002)
Published online: 30 September 2002; | doi:10.1038/nn926
Site-specific fluorescence reveals distinct structural changes with GABA receptor activation and antagonism
Yongchang Chang
& David S. Weiss
Departments of Neurobiology and Physiology & Biophysics, University of Alabama at Birmingham School of Medicine, 1719 Sixth Avenue South CIRC410, Birmingham, Alabama 35294-0021, USA
Neurotransmitter-operated ion channels, such as the GABA (-aminobutyric acid) receptor, are important in fast synaptic transmission between neurons. Using site-specific fluorescent labeling and simultaneous electrophysiological analysis in Xenopus laevis oocytes expressing recombinant 1 GABA receptors, we identified agonist-mediated molecular rearrangements at three positions within and near the agonist-binding pocket that were highly correlated with receptor activation. We also show that competitive antagonists induced distinct rearrangements on their own that stabilized the receptor in a closed state. Finally, the allosteric antagonist picrotoxin induced a global conformational change that was sensed in the subunit−subunit interface of the amino (N)-terminal domain, distant from its presumed site of action within the transmembrane domains. This first detection in real time of molecular rearrangements of a ligand-activated receptor provides insights into the structural correlates of activation, antagonism and allosteric modulation.
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-aminobutyric acid) receptor, are important in fast synaptic transmission between neurons. Using site-specific fluorescent labeling and simultaneous electrophysiological analysis in Xenopus laevis oocytes expressing recombinant 
1 GABA receptors, we identified agonist-mediated molecular rearrangements at three positions within and near the agonist-binding pocket that were highly correlated with receptor activation. We also show that competitive antagonists induced distinct rearrangements on their own that stabilized the receptor in a closed state. Finally, the allosteric antagonist picrotoxin induced a global conformational change that was sensed in the subunit−subunit interface of the amino (N)-terminal domain, distant from its presumed site of action within the transmembrane domains. This first detection in real time of molecular rearrangements of a ligand-activated receptor provides insights into the structural correlates of activation, antagonism and allosteric modulation.
