title: Surface expression of metabotropic glutamate receptor variants mGluR1a and mGluR1b in transfected HEK293 cells.
abstract: Class C G-protein coupled receptors form obligatory dimers. Metabotropic glutamate receptors (mGluRs) are found commonly as homodimers. Alternative splicing of mGluR1 gene results in vivo in the expression of a long variant mGluR1a and at least two short variants mGluR1b and d. The amino acid sequences diverge within their carboxyl-termini six amino acid residues following RRKK motif. This four basic residue sequence was shown to have pronounced impact on function and trafficking of the short variants, while for mGluR1a the long C-terminus reduces the effects caused by presence of the RRKK motif. Here we investigated consequences of interactions between long mGluR1a and short mGluR1b variants. Our results show that mGluR1a interferes with mGluR1b trafficking to the cell surface in HEK293 transfected cells. Expression of a mGlu1a mutant incapable of activating G-proteins with mGluR1b mutated in the glutamate binding site led to the formation of a functional heterodimer. Moreover, we show that swapping long mGluR1a and/or short mGluR1b C-termini with corresponding regions in chimerical GB1 and GB2 gamma-amino butyric acid b (GABAb) receptor subunits do not exclude heterodimerization. These data reveal that the C-terminal ends of mGluR1 do not control subunit association, such that mGluR1 dimers with two distinct C-termini can form and function properly.
authors.affiliation: Institute of Molecular Genetics, Academy of Science of the Czech Republic, Videnska 1083, 14220 Prague 4, Czech Republic.
authors.forename: Jiri
authors.initials: J
authors.lastname: Kumpost
authors.forename: Zdenka
authors.initials: Z
authors.lastname: Syrova
authors.forename: Lenka
authors.initials: L
authors.lastname: Kulihova
authors.forename: Daniela
authors.initials: D
authors.lastname: Frankova
authors.forename: Jean-Charles
authors.initials: JC
authors.lastname: Bologna
authors.forename: Veronika
authors.initials: V
authors.lastname: Hlavackova
authors.forename: Laurent
authors.initials: L
authors.lastname: Prezeau
authors.forename: Michaela
authors.initials: M
authors.lastname: Kralikova
authors.forename: Bohdana
authors.initials: B
authors.lastname: Hruskova
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Pin
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Blahos
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D002118:Calcium / Q000378:metabolism; D002461:Cell Line, Transformed; D015870:Gene Expression / Q000502:physiology*; D006801:Humans; D047468:Immunoprecipitation / Q000379:methods; D016296:Mutagenesis / Q000502:physiology; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D018094:Receptors, Metabotropic Glutamate / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D014162:Transfection / Q000379:methods
chemical_list: D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; D010744:Phosphoric Monoester Hydrolases; C021822:myo-inositol-1 (or 4)-monophosphatase; D002118:Calcium