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Differential Coupling of D1 and D5 Dopamine Receptors to Guanine Nucleotide Binding Proteins in Transfected GH 4 C 1 Rat Somatomammotrophic Cells
Author(s) -
Kimura Kazuhiro,
Sela Shifra,
Bouvier Claudia,
Grandy David K.,
Sidhu Anita
Publication year - 1995
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1995.64052118.x
Subject(s) - receptor , pertussis toxin , g protein , dopamine receptor , agonist , biology , g protein coupled receptor , activator (genetics) , microbiology and biotechnology , biochemistry , chemistry
D1 and D5 dopamine receptor genes, stably expressed in GH 4 C 1 rat somatomammotrophic cells, display identical binding values and stimulate adenylate cyclase. Approximately 60% of D1 receptors were in the agonist high‐affinity state and were converted to the low‐affinity state by 100 µ M guanyl‐5′‐ylimidodiphosphate [Gpp(NH)p]. Of the 48% of D5 receptors in the high‐affinity state, only half were modulated by 100 µ M Gpp(NH)p; in the presence of the G protein activator, AlF 4 − , the high‐affinity sites of D5 receptors were abolished by Gpp(NH)p, suggesting tight coupling between D5 receptors and G proteins. The high‐affinity sites of D1, but not D5, receptors were reduced after pertussis toxin treatment of cells. Thus, whereas D1 receptors in GH 4 C 1 cells couple to both G s , the G stimulatory protein, and a pertussis toxin‐sensitive G protein, D5 receptors couple to G s and a pertussis toxin‐insensitive G protein. Neither D1 nor D5 receptors were able to stimulate phosphoinositide metabolism in these cells. The ability of D5, but not D1, receptors to couple to novel G proteins may be significant in assigning a functional role for these receptors.