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dc.contributor.advisorMihic, S. Johnen
dc.creatorWelsh, Brian Thomasen
dc.date.accessioned2011-01-24T20:05:03Zen
dc.date.accessioned2011-01-24T20:05:46Zen
dc.date.available2011-01-24T20:05:03Zen
dc.date.available2011-01-24T20:05:46Zen
dc.date.issued2010-05en
dc.date.submittedMay 2010en
dc.identifier.urihttp://hdl.handle.net/2152/ETD-UT-2010-05-721en
dc.descriptiontexten
dc.description.abstractThe glycine receptor (GlyR) is a ligand-gated ion channel and member of the nicotinic acetylcholine receptor superfamily. Glycine and the partial agonist taurine are both believed to be the endogenous ligands of the receptor. Partial agonists have lower efficacies than full agonists, eliciting submaximal responses even at saturating concentrations. Recent evidence suggests that efficacy at these receptors is determined by conformational changes that occur early in the process of receptor activation. We previously identified a mutation of the aspartate-97 residue to arginine (D97R), which produces a spontaneously active mutant with behavior that mimics the effects of saturating glycine concentrations on wildtype (WT) GlyR. This D97 residue is hypothesized to form an electrostatic interaction with arginine-119 on an adjacent subunit to stabilize a closed channel closed state. We found that the disruption of this bond converts taurine into a full agonist and greatly increases the efficacies of other [beta]-amino acid partial agonists. Our findings suggest that the determination of efficacy in the GlyR involves the disruption of an inter-subunit electrostatic interaction soon after binding. We next investigated whether the taurine efficacy could be enhanced by ethanol, a well-studied positive allosteric modulator of receptor function. Whole-cell recordings of WT GlyRs demonstrated that alcohol could potentiate the effect of low concentrations of taurine, but did not increase the efficacy of a saturating concentration. Therefore we sought to understand the mechanism by which alcohol enhances the GlyR, because ethanol's actions at inhibitory receptors in the brain are thought to produce many of the physiological effects associated with its use. We examined the effects of 3 [mu]M glycine ± 50 or 200 mM ethanol on outside-out patches expressing WT [alpha]1 GlyR, to determine the effects of alcohol at the single-channel level. Alcohol enhanced GlyR function in a very specific manner. It had minimal effects on open and closed dwell times. Instead, ethanol potentiated GlyR function almost exclusively by increasing burst durations and increasing the number of channel openings per burst, without affecting the percentage of open time within bursts. Kinetic modeling suggests that ethanol increases burst durations by decreasing the rate of glycine unbinding.en
dc.format.mimetypeapplication/pdfen
dc.language.isoengen
dc.subjectGlycine receptoren
dc.subjectEthanolen
dc.subjectSingle channelen
dc.subjectPartial agonismen
dc.subjectTaurineen
dc.titleActivation and allosteric modulation of the [alpha]1 glycine receptoren
dc.date.updated2011-01-24T20:05:46Zen
dc.contributor.committeeMemberAldrich, Richard W.en
dc.contributor.committeeMemberDopico, Alejandro M.en
dc.contributor.committeeMemberHarris, Robert A.en
dc.contributor.committeeMemberZakon, Harold H.en
dc.description.departmentNeuroscience, Institute foren
dc.type.genrethesisen
thesis.degree.departmentNeuroscience, Institute foren
thesis.degree.disciplineNeuroscienceen
thesis.degree.grantorThe University of Texas at Austinen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen


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