title: Molecular cloning, stable expression and desensitization of the human dopamine D1b/D5 receptor.
abstract: The sub-family of dopamine D1-like receptors is now known to be comprised of at least two members: the originally cloned D1 receptor (herein referred to as the D1a receptor) and a related receptor referred to as the D1b, D1 beta or D5 dopamine receptor (herein referred to as the D1b/D5 receptor). Here, we characterize the D1b/D5 receptor expressed transiently in COS-7 cells and permanently in Ltk- cells. Transiently expressed human D1b/D5 receptors bind the D1 specific ligand [125I]SCH 23982 saturably and with high affinity (KD = 500 pM). Competition for [125I]SCH 23982 binding to rat D1b/D5 and human D1a and D1b/D5 receptors supports the contention that the two D1b/D5 receptors are species homologues. Furthermore, in COS-7 cells, as previously observed, dopamine competes for the binding of [125I]SCH 23982 to human D1b/D5 receptors with a higher affinity than that seen at the human D1a receptor. These results are similar to those seen in Ltk- cells permanently transfected with the human D1b/D5 receptor. In these cells, dopamine competition for [125I]SCH 23982 binding is complex, sensitive to guanine nucleotides and of a higher affinity than that observed for dopamine binding to the human D1a receptor expressed in these same cells. In both D1a and D1b/D5 expressing Ltk- cells, dopamine stimulates adenylyl cyclase with an EC50 of approximately 200 nM. Furthermore, preincubation of Ltk- cells expressing the D1a and D1b/D5 receptors with dopamine results in desensitization of the response of adenylyl cyclase to subsequent agonist stimulation.
authors.affiliation: Department of Cell Biology, Duke University Medical Center, Durham, NC 27710.
authors.forename: K R
authors.initials: KR
authors.lastname: Jarvie
authors.forename: M
authors.initials: M
authors.lastname: Tiberi
authors.forename: C
authors.initials: C
authors.lastname: Silvia
authors.forename: J A
authors.initials: JA
authors.lastname: Gingrich
authors.forename: M G
authors.initials: MG
authors.lastname: Caron
mesh_terms: D000262:Adenylyl Cyclases / Q000187:drug effects; D000818:Animals; D001667:Binding, Competitive; D002460:Cell Line; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D006801:Humans; D011954:Receptors, Dopamine / Q000187:drug effects / Q000378:metabolism*; D017447:Receptors, Dopamine D1 / Q000187:drug effects / Q000378:metabolism*; D050641:Receptors, Dopamine D5; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: C493605:DRD5 protein, human; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D011994:Recombinant Proteins; D050641:Receptors, Dopamine D5; D000262:Adenylyl Cyclases