Differential selectivity of M1 and M3 type muscarinic acetylcholine receptors in coupling with a G protein G01 alpha examined in Xenopus oocytes.
The coupling specificities between muscarinic acetylcholine receptors (porcine M1 and M3 subtypes) and a heterotrimeric GTP binding protein (bovine G01) were examined by analysing receptor-stimulated, phospholipase C (PLC)-mediated chloride current responses in Xenopus oocyte expression system. M1-stimulated responses were suppressed by G01 alpha, and this suppression was reversed by expressing exogenous G beta and G gamma, whereas M3-stimulated responses were enhanced by G01 alpha in the presence or absence of G beta and G gamma. G01 alpha itself, when activated directly by intracellular fluoride injection, efficiently activated PLC and stimulated chloride current responses. The results indicate that M1 receptor does not couple with G01, while M3 receptor activates G01 effectively.
Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan.
K
K
Fujii
J
J
Kasahara
K
K
Nakamura
H
H
Sugiyama
D000818:Animals; D002417:Cattle; D004594:Electrophysiology; D005260:Female; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D008845:Microinjections; D009865:Oocytes / Q000737:chemistry / Q000201:enzymology; D010455:Peptides / Q000494:pharmacology; D012333:RNA, Messenger / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000737:chemistry / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013552:Swine; D010738:Type C Phospholipases / Q000378:metabolism; D014981:Xenopus
D010455:Peptides; D012333:RNA, Messenger; D011976:Receptors, Muscarinic; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D019206:GTP-Binding Protein alpha Subunits, Gi-Go