Linked Life Data

17093081

Source:http://linkedlifedata.com/resource/pubmed/id/17093081

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
45
pubmed:dateCreated
2006-11-9
pubmed:abstractText
General anesthetics, including etomidate, act by binding to and enhancing the function of GABA type A receptors (GABA(A)Rs), which mediate inhibitory neurotransmission in the brain. Here, we used a radiolabeled, photoreactive etomidate analog ([(3)H]azietomidate), which retains anesthetic potency in vivo and enhances GABA(A)R function in vitro, to identify directly, for the first time, amino acids that contribute to a GABA(A)R anesthetic binding site. For GABA(A)Rs purified by affinity chromatography from detergent extracts of bovine cortex, [(3)H]azietomidate photoincorporation was increased by GABA and inhibited by etomidate in a concentration-dependent manner (IC(50) = 30 microm). Protein microsequencing of fragments isolated from proteolytic digests established photolabeling of two residues: one within the alphaM1 transmembrane helix at alpha1Met-236 (and/or the homologous methionines in alpha2,3,5), not previously implicated in etomidate function, and one within the betaM3 transmembrane helix at beta3Met-286 (and/or the homologous methionines in beta1,2), an etomidate sensitivity determinant. The pharmacological specificity of labeling indicates that these methionines contribute to a single binding pocket for etomidate located in the transmembrane domain at the interface between beta and alpha subunits, in what is predicted by structural models based on homology with the nicotinic acetylcholine receptor to be a water-filled pocket approximately 50 A below the GABA binding site. The localization of the etomidate binding site to an intersubunit, not an intrasubunit, binding pocket is a novel conclusion that suggests more generally that the localization of drug binding sites to subunit interfaces may be a feature not only for GABA and benzodiazepines but also for etomidate and other intravenous and volatile anesthetics.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
1529-2401
pubmed:author
pubmed:issnType
Electronic
pubmed:day
8
pubmed:volume
26
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
11599-605
pubmed:dateRevised
2007-12-3
pubmed:meshHeading
pubmed-meshheading:17093081-Animals, pubmed-meshheading:17093081-Binding Sites, pubmed-meshheading:17093081-Blotting, Western, pubmed-meshheading:17093081-Brain, pubmed-meshheading:17093081-Cattle, pubmed-meshheading:17093081-Chromatography, High Pressure Liquid, pubmed-meshheading:17093081-Dose-Response Relationship, Drug, pubmed-meshheading:17093081-Etomidate, pubmed-meshheading:17093081-GABA Agonists, pubmed-meshheading:17093081-Hypnotics and Sedatives, pubmed-meshheading:17093081-Inhibitory Concentration 50, pubmed-meshheading:17093081-Methionine, pubmed-meshheading:17093081-Models, Molecular, pubmed-meshheading:17093081-Muscimol, pubmed-meshheading:17093081-Photoaffinity Labels, pubmed-meshheading:17093081-Radioligand Assay, pubmed-meshheading:17093081-Receptors, GABA, pubmed-meshheading:17093081-Sequence Analysis, Protein, pubmed-meshheading:17093081-Subcellular Fractions, pubmed-meshheading:17093081-Tritium, pubmed-meshheading:17093081-gamma-Aminobutyric Acid
pubmed:year
2006
pubmed:articleTitle
Identification of a GABAA receptor anesthetic binding site at subunit interfaces by photolabeling with an etomidate analog.
pubmed:affiliation
Department of Molecular and Medical Pharmacology, Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't, Research Support, N.I.H., Extramural