title: Assembly and ligand binding properties of the water-soluble extracellular domains of the glutamate receptor 1 subunit.
abstract: High resolution structural studies of models of glutamate receptors (GluRs) have been limited to monomeric models of the ligand-binding site. To obtain oligomeric models of glutamate receptors that can reveal more complete structural information, we examined the assembly and ligand binding properties of two truncated versions of the GluR1 subunit. The first version, GluR1-WS, consisted of only the N-terminal extracellular segment (Ala(1)-Glu(520)) bridged by a synthetic linker to the second extracellular domain (Asn(615)-Gly(790)). The second version, GluR1-M1, consisted of the first N-terminal extracellular domain (Ala(1)-Glu(520)) bridged by a synthetic linker to a second segment containing the second extracellular domain, the third transmembrane domain, and the intracellular C-terminal domain (Asn(615)-Leu(889)). When expressed in Xenopus oocytes, GluR-WS was secreted and water-soluble; GluR1-M1 was displayed on the surface of oocytes. GluR1-WS exhibited a velocity sedimentation profile that was consistent with assembly of homooligomers and bound the glutamate receptor agonist alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid with high affinity. These findings show that the extracellular domains of GluR1 that are sufficient for ligand binding apparently are sufficient for subunit assembly and might be a suitable target for structural studies of a water-soluble GluR1 oligomer.
authors.affiliation: Neuroscience Center of Excellence and the Department of Neurology, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
authors.forename: G B
authors.initials: GB
authors.lastname: Wells
authors.forename: L
authors.initials: L
authors.lastname: Lin
authors.forename: E M
authors.initials: EM
authors.lastname: Jeanclos
authors.forename: R
authors.initials: R
authors.lastname: Anand
mesh_terms: D000818:Animals; D008024:Ligands; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009865:Oocytes / Q000378:metabolism; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D018091:Receptors, AMPA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012995:Solubility; D014162:Transfection; D014316:Tritium; D014867:Water / Q000737:chemistry; D014982:Xenopus laevis; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000378:metabolism
chemical_list: D008024:Ligands; D008565:Membrane Proteins; D018091:Receptors, AMPA; D014316:Tritium; D014867:Water; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid