title: Identification and characterization of heptapeptide modulators of the glycine receptor.
abstract: The glycine receptor is a member of the Cys-loop receptor superfamily of ligand-gated ion channels and is implicated as a possible therapeutic target for the treatment of diseases such as alcoholism and inflammatory pain. In humans, four glycine receptor subtypes (α1, α2, α3, and β) co-assemble to form pentameric channel proteins as either α homomers or αβ heteromers. To date, few agents have been identified that can selectively modulate the glycine receptor, especially those possessing subtype specificity. We used a cell-based method of phage display panning, coupled with two-electrode voltage-clamp electrophysiology in Xenopus laevis oocytes, to identify novel heptapeptide modulators of the α1β glycine receptor. This involved a panning procedure in which the phage library initially underwent subtractive panning against Human Embryonic Kidney (HEK) 293 cells expressing alternative glycine receptor subtypes before panning the remaining library over HEK 293 cells expressing the target, the α1β glycine receptor. Peptides were identified that act with selectivity on α1β and α3β, compared to α2β, glycine receptors. In addition, peptide activity at the glycine receptor decreased when zinc was chelated by tricine, similar to previous observations of a decrease in ethanol's enhancing actions at the receptor in the absence of zinc. Comparisons of the amino acid sequences of heptapeptides capable of potentiating glycine receptor function revealed several consensus sequences that may be predictive of a peptide's enhancing ability.
authors.affiliation: Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol & Addiction Research, Institutes for Neuroscience and Cell & Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Garrett L
authors.initials: GL
authors.lastname: Cornelison
authors.affiliation: Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol & Addiction Research, Institutes for Neuroscience and Cell & Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Natasha C
authors.initials: NC
authors.lastname: Pflanz
authors.affiliation: Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol & Addiction Research, Institutes for Neuroscience and Cell & Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Tipps
authors.affiliation: Department of Neuroscience, Division of Pharmacology and Toxicology, Waggoner Center for Alcohol & Addiction Research, Institutes for Neuroscience and Cell & Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA. Electronic address: mihic@austin.utexas.edu.
authors.forename: S John
authors.initials: SJ
authors.lastname: Mihic
mesh_terms: D000494:Allosteric Regulation / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D016384:Consensus Sequence; D055724:Electrophysiological Phenomena / Q000187:drug effects; D057809:HEK293 Cells; D006801:Humans; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology*; D018009:Receptors, Glycine / Q000737:chemistry / Q000378:metabolism*; D014982:Xenopus laevis; D015032:Zinc / Q000378:metabolism
chemical_list: D009842:Oligopeptides; D018009:Receptors, Glycine; D015032:Zinc
keywords: Allosteric modulator; Electrophysiology; Glycine receptor; Phage display; Xenopus oocytes