title: Ligand-induced rearrangement of the dimeric metabotropic glutamate receptor 1alpha.
abstract: The extracellular domain of the metabotropic glutamate receptor 1alpha (mGluR1alpha) forms a dimer and the ligand, glutamate, induces a structural rearrangement in this domain. However, the conformational change in the cytoplasmic domain, which is critical for mGluR1alpha's interaction with G proteins, remains unclear. Here we investigated the ligand-induced conformational changes in the cytoplasmic domain by fluorescence resonance energy transfer (FRET) analysis of mGluR1alpha labeled with fluorescent protein(s) under total internal reflection field microscopy. Upon ligand binding, the intersubunit FRET efficiency between the second loops increased, whereas that between first loops decreased. In contrast, the intrasubunit FRET did not change clearly. These results show that ligand binding does not change the structure of each subunit, but does change the dimeric allocation of the cytoplasmic regions, which may underlie downstream signaling.
authors.affiliation: Division of Biophysics and Neurobiology, Department of Molecular Physiology, National Institute for Physiological Sciences, 38 Nishigonaka Myodaiji, Okazaki, 444-8585, Japan. tateyama@nips.ac.jp
authors.forename: Michihiro
authors.initials: M
authors.lastname: Tateyama
authors.forename: Hideki
authors.initials: H
authors.lastname: Abe
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Nakata
authors.forename: Osamu
authors.initials: O
authors.lastname: Saito
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kubo
mesh_terms: D019281:Dimerization; D004735:Energy Transfer; D005453:Fluorescence; D008024:Ligands; D018094:Receptors, Metabotropic Glutamate / Q000737:chemistry / Q000378:metabolism*
chemical_list: D008024:Ligands; D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1