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Three classes of propofol binding sites on GABAA receptors.
Chen, Zi-Wei; Chintala, Satyanarayana M; Bracamontes, John; Sugasawa, Yusuke; Pierce, Spencer R; Varga, Balazs R; Smith, Edward H; Edge, Christopher J; Franks, Nicholas P; Cheng, Wayland W L; Akk, Gustav; Evers, Alex S.
Affiliation
  • 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 Med
J Biol Chem ; 300(10): 107778, 2024 Sep 11.
Article in En | MEDLINE | ID: mdl-39270821
ABSTRACT
Propofol is a widely used anesthetic and sedative that acts as a positive allosteric modulator of gamma-aminobutyric acid type A (GABAA) 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 ß-H267, a pore-lining residue, whereas AziPm labels residues ß-M286, ß-M227, and α-I239 in the two membrane-facing interfaces [ß(+)/α(-) and α(+)/ß(-)] between α and ß subunits. This study used photoaffinity labeling of α1ß3 GABAA receptors to reconcile the apparently conflicting results obtained with AziPm and o-PD labeling, focusing on whether ß3-H267 identifies specific propofol binding site(s). The results show that propofol, but not AziPm protects ß3-H267 from labeling by o-PD, whereas both propofol and o-PD protect against AziPm labeling of ß3-M286, ß3-M227, and α1I239. 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 ß3 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 ß-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 α1ß3 GABAA receptors.
Key words

Full text: 1 Collection: 01-internacional Database: MEDLINE Language: En Journal: J Biol Chem Year: 2024 Document type: Article Affiliation country: United States Country of publication: United States

Full text: 1 Collection: 01-internacional Database: MEDLINE Language: En Journal: J Biol Chem Year: 2024 Document type: Article Affiliation country: United States Country of publication: United States