Three classes of propofol binding sites on GABA A receptors.

Autor:	Chen ZW; Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; The Taylor Family Institute for Innovative Psychiatric Research Washington University School of Medicine, St Louis, Missouri, USA., Chintala SM; Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA., Bracamontes J; Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA., Sugasawa Y; Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan., Pierce SR; Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA., Varga BR; Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA., Smith EH; Department of Life Sciences, Imperial College, London, UK., Edge CJ; Department of Life Sciences, Imperial College, London, UK., Franks NP; Department of Life Sciences, Imperial College, London, UK; UK Dementia Research Institute, Imperial College, London, UK., Cheng WWL; Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA., Akk G; Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; The Taylor Family Institute for Innovative Psychiatric Research Washington University School of Medicine, St Louis, Missouri, USA., Evers AS; Department of Anesthesiology, Washington University School of Medicine, St Louis, Missouri, USA; Department of Developmental Biology, Washington University School of Medicine, St Louis, Missouri, USA; The Taylor Family Institute for Innovative Psychiatric Research Washington University School of Medicine, St Louis, Missouri, USA. Electronic address: eversa@wustl.edu.
Jazyk:	angličtina
Zdroj:	The Journal of biological chemistry [J Biol Chem] 2024 Oct; Vol. 300 (10), pp. 107778. Date of Electronic Publication: 2024 Sep 11.
DOI:	10.1016/j.jbc.2024.107778
Abstrakt:	Propofol is a widely used anesthetic and sedative that acts as a positive allosteric modulator of gamma-aminobutyric acid type A (GABA A ) receptors. Several potential propofol binding sites that may mediate this effect have been identified using propofol-analogue photoaffinity labeling. Ortho-propofol diazirine (o-PD) labels β-H267, a pore-lining residue, whereas AziPm labels residues β-M286, β-M227, and α-I239 in the two membrane-facing interfaces [β(+)/α(-) and α(+)/β(-)] between α and β subunits. This study used photoaffinity labeling of α 1 β 3 GABA A receptors to reconcile the apparently conflicting results obtained with AziPm and o-PD labeling, focusing on whether β 3 -H267 identifies specific propofol binding site(s). The results show that propofol, but not AziPm protects β 3 -H267 from labeling by o-PD, whereas both propofol and o-PD protect against AziPm labeling of β 3 -M286, β 3 -M227, and α 1 I239. These data indicate that there are three distinct classes of propofol binding sites, with AziPm binding to two of the classes and o-PD to all three. Analysis of binding stoichiometry using native mass spectrometry in β 3 homomeric receptors, demonstrated a minimum of five AziPm labeled residues and three o-PD labeled residues per pentamer, suggesting that there are two distinct propofol binding sites per β-subunit. The native mass spectrometry data, coupled with photolabeling performed in the presence of zinc, indicate that the binding site(s) identified by o-PD are adjacent to, but not within the channel pore, since the pore at the 17' H267 residue can accommodate only one propofol molecule. These data validate the existence of three classes of specific propofol binding sites on α 1 β 3 GABA A receptors. Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article. (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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