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dc.contributor.authorNirthanan, Selvanayagamen_US
dc.contributor.authorIII, Galo Garciaen_US
dc.contributor.authorC. Chiara, Daviden_US
dc.contributor.authorShaukat Husain, S.en_US
dc.contributor.authorB. Cohen, Jonathanen_US
dc.date.accessioned2017-05-03T15:28:59Z
dc.date.available2017-05-03T15:28:59Z
dc.date.issued2008en_US
dc.date.modified2014-10-08T01:43:49Z
dc.identifier.issn1083351Xen_US
dc.identifier.doi10.1074/jbc.M801332200en_US
dc.identifier.urihttp://hdl.handle.net/10072/26747
dc.description.abstractEtomidate, one of the most potent general anesthetics used clinically, acts at micromolar concentrations as an anesthetic and positive allosteric modulator of gamma-aminobutyric acid responses, whereas it inhibits muscle-type nicotinic acetylcholine receptors (nAChRs) at concentrations above 10 microm. We report here that TDBzl-etomidate, a photoreactive etomidate analog, acts as a positive allosteric nAChR modulator rather than an inhibitor, and we identify its binding sites by photoaffinity labeling. TDBzl-etomidate (>10 microm) increased the submaximal response to acetylcholine (10 microm) with a 2.5-fold increase at 60 microm. At higher concentrations, it inhibited the binding of the noncompetitive antagonists [(3)H]tetracaine and [(3)H]phencyclidine to Torpedo nAChR-rich membranes (IC(50) values of 0. 8 mm). nAChR-rich membranes were photolabeled with [(3)H]TDBzl-etomidate, and labeled amino acids were identified by Edman degradation. For nAChRs photolabeled in the absence of agonist (resting state), there was tetracaine-inhibitable photolabeling of amino acids in the ion channel at positions M2-9 (deltaLeu-265) and M2-13 (alphaVal-255 and deltaVal-269), whereas labeling of alphaM2-10 (alphaSer-252) was not inhibited by tetracaine but was enhanced 10-fold by proadifen or phencyclidine. In addition, there was labeling in gammaM3 (gammaMet-299), a residue that contributes to the same pocket in the nAChR structure as alphaM2-10. The pharmacological specificity of labeling of residues, together with their locations in the nAChR structure, indicate that TDBzl-etomidate binds at two distinct sites: one within the lumen of the ion channel (labeling of M2-9 and -13), an inhibitory site, and another at the interface between the alpha and gamma subunits (labeling of alphaM2-10 and gammaMet-299) likely to be a site for positive allosteric modulation.en_US
dc.description.peerreviewedYesen_US
dc.description.publicationstatusYesen_US
dc.format.extent2795529 bytes
dc.format.mimetypeapplication/pdf
dc.languageEnglishen_US
dc.language.isoen_US
dc.publisherAmerican Society for Biochemistry and Molecular Biologyen_US
dc.publisher.placeBethesdaen_US
dc.relation.ispartofstudentpublicationNen_US
dc.relation.ispartofpagefrom22051en_US
dc.relation.ispartofpageto22062en_US
dc.relation.ispartofissue32en_US
dc.relation.ispartofjournalJournal of Biological Chemistryen_US
dc.relation.ispartofvolume283en_US
dc.rights.retentionYen_US
dc.subject.fieldofresearchAnaesthesiologyen_US
dc.subject.fieldofresearchCellular Nervous Systemen_US
dc.subject.fieldofresearchcode110301en_US
dc.subject.fieldofresearchcode110902en_US
dc.titleIdentification of binding sites in the nicotinic acetylcholine receptor for TDBzl-etomidate, a photoreactive positive allosteric effector.en_US
dc.typeJournal articleen_US
dc.type.descriptionC1 - Peer Reviewed (HERDC)en_US
dc.type.codeC - Journal Articlesen_US
gro.rights.copyrightThis research was originally published in Journal of Biological Chemistry (JBC). Selvanayagam Nirthanan, Galo Garcia III, David C. Chiara, S. Shaukat Husain§, Jonathan B. Cohen, Identification of binding sites in the nicotinic acetylcholine receptor for TDBzl-etomidate, a photoreactive positive allosteric effector Journal of Biological Chemistry (JBC), 2008; 283: 22051-22062. Copyright the American Society for Biochemistry and Molecular Biology. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitve version.en_US
gro.date.issued2008
gro.hasfulltextFull Text


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