title: Multiple coupling of human D5 dopamine receptors to guanine nucleotide binding proteins Gs and Gz.
abstract: We have demonstrated previously that D1 dopamine receptors are coupled to both Gs alpha and Go alpha. We examine here the coupling between human D5 dopamine receptors and G proteins in transfected rat pituitary GH4C1 cells. Similar to D1 receptors, cholera toxin treatment of cells reduced, but did not abolish, D5 agonist high-affinity binding sites, indicating D5 receptors couple to both Gs alpha and cholera toxin-insensitive G proteins. The interaction between D5 receptors and Gs alpha was confirmed by immunoprecipitation studies and by the ability of D5 receptors to stimulate adenylyl cyclase. Unlike D1 receptors, D5 receptors did not display any pertussis toxin-sensitive G-protein coupling to Go alpha or Gi alpha. D5 receptors were also not coupled to Gq alpha and were unable to mediate phosphatidylinositol metabolism. Instead, D5 sites appeared to be coupled to an AIF(-)4-sensitive, N-ethylmaleimide-resistant G protein. Anti-Gz alpha caused immunoprecipitation of 24.2 +/- 5.2% of G protein-associated D5 receptors, indicating coupling between D5 and Gz alpha. The coupling to Gz alpha was specific for D5 receptors, because similar associations were not detected between D1 receptors and Gz alpha.
authors.affiliation: Department of Pediatrics, Georgetown University Medical Center, Washington, DC 20007, USA.
authors.forename: A
authors.initials: A
authors.lastname: Sidhu
authors.forename: K
authors.initials: K
authors.lastname: Kimura
authors.forename: M
authors.initials: M
authors.lastname: Uh
authors.forename: B H
authors.initials: BH
authors.lastname: White
authors.forename: S
authors.initials: S
authors.lastname: Patel
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane; D044385:GTP-Binding Protein alpha Subunits; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D006150:Guanine Nucleotides / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D010902:Pituitary Gland / Q000166:cytology / Q000378:metabolism; D011233:Precipitin Tests; D051381:Rats; D017447:Receptors, Dopamine D1 / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D050641:Receptors, Dopamine D5; D012995:Solubility; D014162:Transfection
chemical_list: C493605:DRD5 protein, human; C493607:Drd5 protein, rat; C099387:GNAZ protein, human; D044385:GTP-Binding Protein alpha Subunits; C490963:Gnaz protein, rat; D006150:Guanine Nucleotides; D007106:Immune Sera; D017447:Receptors, Dopamine D1; D050641:Receptors, Dopamine D5; D019204:GTP-Binding Proteins; D019205:GTP-Binding Protein alpha Subunits, Gs; D020962:Heterotrimeric GTP-Binding Proteins