Adenylyl cyclase interaction with the D2 dopamine receptor family; differential coupling to Gi, Gz, and Gs.
1. The D2-type dopamine receptors are thought to inhibit adenylyl cyclase (AC), via coupling to pertussis toxin (PTX)-sensitive G proteins of the Gi family. We examined whether and to what extent the various D2 receptors (D2S, D2L, D3S, D3L, and D4) couple to the PTX-insensitive G protein Gz, to produce inhibition of AC activity. 2. COS-7 cells were transiently transfected with the individual murine dopamine receptors alone, as well as together with the alpha subunit of Gz. PTX treatment was employed to inactivate endogenous alpha i, and coupling to Gi and Gz was estimated by measuring the inhibition of cAMP accumulation induced by quinpirole, in forskolin-stimulated cells. 3. D2S or D2L receptors can couple to the same extent to Gi and to Gz. The D4 dopamine receptor couples preferably to Gz, resulting in about 60% quinpirole-induced inhibition of cAMP accumulation. The D3S and D3L receptor isoforms couple slightly to Gz and result in 15 and 30% inhibition of cAMP accumulation, respectively. 4. We have demonstrated for the first time that the two D3 receptor isoforms, and not any of the other D2 receptor subtypes, also couple to Gs in both COS-7 and CHO transfected cells, in the presence of PTX. 5. Thus, the differential coupling of the D2 dopamine receptor subtypes to various G proteins may add another aspect to the diversity of dopamine receptor function.
Obadiah
J
J
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel.
Avidor-Reiss
T
T
Fishburn
C S
CS
Carmon
S
S
Bayewitch
M
M
Vogel
Z
Z
Fuchs
S
S
Levavi-Sivan
B
B
D037361:Adenylate Cyclase Toxin; D000262:Adenylyl Cyclases / Q000187:drug effects*; D000818:Animals; D016466:CHO Cells; D019556:COS Cells; D006224:Cricetinae; D000242:Cyclic AMP / Q000096:biosynthesis*; D018491:Dopamine Agonists / Q000494:pharmacology; D044385:GTP-Binding Protein alpha Subunits; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000187:drug effects / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D020962:Heterotrimeric GTP-Binding Proteins; D037342:Pertussis Toxin; D019257:Quinpirole / Q000494:pharmacology; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D050637:Receptors, Dopamine D3; D050638:Receptors, Dopamine D4; D014162:Transfection / Q000235:genetics; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D018491:Dopamine Agonists; D044385:GTP-Binding Protein alpha Subunits; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D010566:Virulence Factors, Bordetella; D050638:Receptors, Dopamine D4; D019257:Quinpirole; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D020962:Heterotrimeric GTP-Binding Proteins; D000262:Adenylyl Cyclases