Propofol is the most important intravenous general anesthetic in current clinical use. It acts by potentiating GABAA (γ-aminobutyric acid type A) receptors, but where it binds to this receptor is not known and has been a matter of some debate. We synthesized a new propofol analog photolabeling reagent whose biological activity is very similar to that of propofol. We confirmed that this reagent labeled known propofol binding sites in human serum albumin that have been identified using X-ray crystallography. Using a combination of protiated and deuterated versions of the reagent to label mammalian receptors in intact membranes, we identified a new binding site for propofol in GABAA receptors consisting of both β3 homopentamers and α1β3 heteropentamers. The binding site is located within the β subunit at the interface between the transmembrane domains and the extracellular domain and lies close to known determinants of anesthetic sensitivity in the transmembrane segments TM1 and TM2.
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We thank the Medical Research Council (UK) (grant G0901892 to N.P.F.), the US National Institutes of Health (NIH) - National Institute of General Medical Sciences (grant PO1-GM47969 to A.S.E. and grant 8 P41 GM103422-35 to R.R.T.), the Austrian Ministry of Science and Research and the European Seventh Framework Program (grant HEALTH-F4-2008-202088 to W.S.) for support. We also thank R. Yustos for technical assistance and D. Droste, M. Bennett, T. Gent, K. Karu, B. Manion, R. Ruby and J. Malone for help with the experiments.
The authors declare no competing financial interests.
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Yip, G., Chen, Z., Edge, C. et al. A propofol binding site on mammalian GABAA receptors identified by photolabeling. Nat Chem Biol 9, 715–720 (2013). https://doi.org/10.1038/nchembio.1340
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