title: A single amino acid residue controls Ca2+ signaling by an octopamine receptor from Drosophila melanogaster.
abstract: Rhythmic activity of cells and cellular networks plays an important role in physiology. In the nervous system oscillations of electrical activity and/or second messenger concentrations are important to synchronize neuronal activity. At the molecular level, rhythmic activity can be initiated by different routes. We have recently shown that an octopamine-activated G-protein-coupled receptor (GPCR; DmOctα1Rb, CG3856) from Drosophila initiates Ca(2+) oscillations. Here, we have unraveled the molecular basis of cellular Ca(2+) signaling controlled by the DmOctα1Rb receptor using a combination of pharmacological intervention, site-directed mutagenesis, and functional cellular Ca(2+) imaging on heterologously expressed receptors. Phosphorylation of a single amino acid residue in the third intracellular loop of the GPCR by PKC is necessary and sufficient to desensitize the receptor. From its desensitized state, DmOctα1Rb is resensitized by dephosphorylation, and a new Ca(2+) signal occurs on octopamine stimulation. Our findings show that transient changes of the receptor's surface profile have a strong effect on its physiological signaling properties. We expect that the detailed knowledge of DmOctα1Rb-dependent signal transduction fosters the identification of specific drugs that can be used for GPCR-mediated pest control, since octopamine serves important physiological and behavioral functions in arthropods.
authors.affiliation: Institute of Complex Systems, Zellulaere Biophysik (ICS-4), Forschungszentrum Juelich, 52425 Juelich, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Hoff
authors.forename: Sabine
authors.initials: S
authors.lastname: Balfanz
authors.forename: Petra
authors.initials: P
authors.lastname: Ehling
authors.forename: Thomas
authors.initials: T
authors.lastname: Gensch
authors.forename: Arnd
authors.initials: A
authors.lastname: Baumann
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D004963:Estrenes / Q000494:pharmacology; D005470:Fluorometry; D057809:HEK293 Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008301:Maleimides / Q000494:pharmacology; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009655:Octopamine / Q000378:metabolism / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D011760:Pyrrolidinones / Q000494:pharmacology; D017982:Receptors, Biogenic Amine / Q000235:genetics / Q000378:metabolism*; D013912:Threonine / Q000235:genetics / Q000378:metabolism*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D004963:Estrenes; D007211:Indoles; D008301:Maleimides; D010726:Phosphodiesterase Inhibitors; D011760:Pyrrolidinones; D017982:Receptors, Biogenic Amine; C027604:norsynephrine receptor; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D009655:Octopamine; D013912:Threonine; D011493:Protein Kinase C; D010738:Type C Phospholipases; C088060:bisindolylmaleimide; D002118:Calcium