Functional coupling of Gi subtype with GABAB receptor/adenylyl cyclase system: analysis using a reconstituted system with purified GTP-binding protein from bovine cerebral cortex.
A single molecular species of GTP-binding protein (G protein) has been purified from the bovine cerebral cortex. The immunoblot analysis indicated that the isolated G protein might be Gi1 or Gi2 but not Go, since it was reacted by specific antibodies, anti-Gi alpha 1-2 and anti-Gi alpha 1-1, but not anti-Go alpha. When the Gi protein was reconstituted into phospholipid vesicles with partially purified GABAB receptor and adenylyl cyclase, the stimulation of GABAB receptor by its agonists induced the inhibition of forskolin-stimulated cAMP accumulation. This GABA-induced inhibition was abolished by CGP 55845A, an antagonist of GABAB receptor. These results suggest that a Gi subtype, which was suggested to correspond to Gi1 or Gi2 may be functionally coupled with GABAB receptor/adenylyl cyclase system.
Nishikawa
M
M
Department of Pharmacology, Kyoto Prefectural University of Medicine, Japan.
Hirouchi
M
M
Kuriyama
K
K
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002540:Cerebral Cortex / Q000378:metabolism*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000302:isolation & purification / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008081:Liposomes; D010743:Phospholipids / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000378:metabolism
D008081:Liposomes; D010743:Phospholipids; D011963:Receptors, GABA-A; D018080:Receptors, GABA-B; D019204:GTP-Binding Proteins; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D000262:Adenylyl Cyclases