%0 Journal Article
%A Chiara, David
C.
%A Dostalova, Zuzana
%A Jayakar, Selwyn S.
%A Zhou, Xiaojuan
%A Miller, Keith W.
%A Cohen, Jonathan B.
%D 2012
%T Mapping General Anesthetic
Binding Site(s) in Human α1β3 γ-Aminobutyric Acid
Type A Receptors with [3H]TDBzl-Etomidate, a Photoreactive
Etomidate Analogue
%U https://acs.figshare.com/articles/journal_contribution/Mapping_General_Anesthetic_Binding_Site_s_in_Human_1_3_Aminobutyric_Acid_Type_A_Receptors_with_sup_3_sup_H_TDBzl_Etomidate_a_Photoreactive_Etomidate_Analogue/2555494
%R 10.1021/bi201772m.s001
%2 https://acs.figshare.com/ndownloader/files/4198555
%K photolabeled GABAAR
%K α M 1
%K α M 2
%K β M 1
%K GABAAR transmembrane domain
%K GLIC
%K docking studies
%K α1β3 GABAAR
%K β M 3 transmembrane helices
%K Met
%K GABAAR intersubunit etomidate binding site
%K residue photolabeled
%K etomidate binding site
%K GABAAR etomidate binding sites
%K β3 M 3 transmembrane helix
%K chemical structures
%K β M 2 helices
%K aryl diazirine
%K allosteric modulators
%K GABAAR homology models
%K acid side chain reactivity
%K α subunits
%X The γ-aminobutyric acid type A receptor (GABAAR) is a target for general anesthetics of diverse chemical
structures, which act as positive allosteric modulators at clinical
doses. Previously, in a heterogeneous mixture of GABAARs
purified from bovine brain, [3H]azietomidate photolabeling
of αMet-236 and βMet-286 in the αM1 and βM3
transmembrane helices identified an etomidate binding site in the
GABAAR transmembrane domain at the interface between the
β and α subunits [Li, G. D., et.al. (2006) J.
Neurosci. 26, 11599–11605]. To further define GABAAR etomidate binding sites, we now use [3H]TDBzl-etomidate,
an aryl diazirine with broader amino acid side chain reactivity than
azietomidate, to photolabel purified human FLAG-α1β3 GABAARs and more extensively identify photolabeled GABAAR amino acids. [3H]TDBzl-etomidate photolabeled in an
etomidate-inhibitable manner β3Val-290, in the β3M3 transmembrane
helix, as well as α1Met-236 in α1M1, a residue photolabeled
by [3H]azietomidate, while no photolabeling of amino acids
in the αM2 and βM2 helices that also border the etomidate
binding site was detected. The location of these photolabeled amino
acids in GABAAR homology models derived from the recently
determined structures of prokaryote (GLIC) or invertebrate (GluCl)
homologues
and the results of computational docking studies predict the orientation
of [3H]TDBzl-etomidate bound in that site and the other
amino acids contributing to this GABAAR intersubunit etomidate
binding site. Etomidate-inhibitable photolabeling of β3Met-227
in βM1 by [3H]TDBzl-etomidate and [3H]azietomidate
also provides evidence of a homologous etomidate binding site at the
β3−β3 subunit interface in the α1β3
GABAAR.
%I ACS Publications