title: Arthropod D2 receptors positively couple with cAMP through the Gi/o protein family.
abstract: The pyloric network is an important model system for understanding neuromodulation of rhythmic motor behaviors like breathing or walking. Dopamine (DA) differentially modulates neurons within the pyloric network. However, while the electrophysiological actions of DA have been well characterized, nothing is known about the signaling events that mediate its effects. We have begun a molecular characterization of DA receptors (DARs) in this invertebrate system. Here, we describe the cloning and characterization of the lobster D(2) receptor, D(2 alpha Pan). We found that when expressed in HEK cells, the D(2 alpha Pan) receptor is activated by DA, but not other monoamines endogenous to the lobster nervous system. This receptor positively couples with cAMP through multiple Gi/o proteins via two discrete pathways: 1) a G alpha mediated inhibition of adenylyl cyclase (AC), leading to a decrease in cAMP and 2) a G beta gamma-mediated activation of phospholipase C beta (PLC beta), leading to an increase in cAMP. Alternate splicing alters the potency and efficacy of the receptor, but does not affect monoamine specificity. Finally, we show that arthropod D(2) receptor coupling with cAMP varies with the cellular milieu.
authors.affiliation: Program for Cell and Molecular Biology and Physiology, Department of Biology, Georgia State University, P.O. Box 4010, Atlanta, Georgia 30303, USA.
authors.forename: Merry C
authors.initials: MC
authors.lastname: Clark
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: Baro
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism*; D004298:Dopamine / Q000494:pharmacology; D015259:Dopamine Agents / Q000494:pharmacology*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D033521:Palinuridae / Q000235:genetics / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
chemical_list: D015259:Dopamine Agents; D017448:Receptors, Dopamine D2; D000242:Cyclic AMP; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D000262:Adenylyl Cyclases; D004298:Dopamine