Mutational analysis of the putative high-affinity propofol binding site in human beta 3 homomeric GABA(A) receptors
Author(s)
Type
Journal Article
Abstract
Propofol is a sedative and anesthetic agent that can both activate GABAA receptors and potentiate receptor activation elicited by submaximal concentrations of the transmitter. A recent modeling study of the β3 homomeric GABAA receptor postulated a high-affinity propofol binding site in a hydrophobic pocket in the middle of a triangular cleft lined by the M1 and M2 membrane-spanning domains of one subunit and the M2 domain of the neighboring subunit. The goal of the present study was to gain functional evidence for the involvement of this pocket in the actions of propofol. Human β3 and α1β3 receptors were expressed in Xenopus oocytes, and the effects of substitutions of selected residues were probed on channel activation by propofol and pentobarbital. The data demonstrate the vital role of the β3(Y143), β3(F221), β3(Q224), and β3(T266) residues in the actions of propofol but not pentobarbital in β3 receptors. The effects of β3(Y143W) and β3(Q224W) on activation by propofol are likely steric because propofol analogs with less bulky ortho substituents activated both wild-type and mutant receptors. The T266W mutation removed activation by propofol in β3 homomeric receptors; however, this mutation alone or in combination with a homologous mutation (I271W) in the α1 subunit had almost no effect on activation properties in α1β3 heteromeric receptors. We hypothesize that heteromeric α1β3 receptors can be activated by propofol interactions with β3–β3, α1–β3, and β3–α1 interfaces, but the exact locations of the binding site and/or nature of interactions vary in different classes of interfaces.
Date Issued
2015-10-01
Date Acceptance
2015-07-23
Citation
Molecular Pharmacology, 2015, 88 (4), pp.736-745
ISSN
1521-0111
Publisher
American Society for Pharmacology and Experimental Therapeutics (ASPET)
Start Page
736
End Page
745
Journal / Book Title
Molecular Pharmacology
Volume
88
Issue
4
Copyright Statement
© 2015 by The American Society for Pharmacology and Experimental Therapeutics
Sponsor
Medical Research Council (MRC)
Medical Research Council (MRC)
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000361034700011&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
G0501584
G0901892
Subjects
Science & Technology
Life Sciences & Biomedicine
Pharmacology & Pharmacy
A RECEPTORS
SUBUNIT
ETOMIDATE
MODULATION
ACTIVATION
NEURONS
POTENTIATION
DOMAIN
ANALOG
CELLS
Animals
Binding Sites
DNA Mutational Analysis
Dose-Response Relationship, Drug
Female
Humans
Mutation
Propofol
Protein Structure, Secondary
Receptors, GABA-A
Xenopus laevis
1115 Pharmacology And Pharmaceutical Sciences
1109 Neurosciences
Publication Status
Published