Pertussis toxin-sensitive G-proteins in the sino-atrial node and right atrium of bovine heart.
Three apparently distinct pertussis toxin (PTX)-sensitive substrates, with Mrs of 39, 40 and 41 kDa, were identified in membranes prepared from the sino-atrial (SA) node and right atrium of bovine heart. Based on their biochemical characterization, the effects of guanine nucleotides/MgCl2 on their PTX-catalyzed [32P]ADP ribosylation, and the PTX-induced decrease in radiolabelled agonist high-affinity binding to muscarinic acetylcholine receptors present in these membranes, we tentatively identify these proteins as the alpha-subunits of the G0 and Gi subtypes of G-proteins. These results indicate that PTX alters the G-protein modulation of SA nodal and atrial muscarinic acetylcholine receptors by disrupting at least one of a group of PTX-sensitive G-proteins present in these tissues.
Braun
A P
AP
Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Canada.
Gupta
R C
RC
Sulakhe
P V
PV
D000244:Adenosine Diphosphate / Q000378:metabolism; D000818:Animals; D002417:Cattle; D019204:GTP-Binding Proteins / Q000378:metabolism*; D008566:Membranes / Q000648:ultrastructure; D018727:Muscarinic Antagonists; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D010095:Oxotremorine / Q000378:metabolism; D037342:Pertussis Toxin; D010761:Phosphorus Radioisotopes; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism; D012849:Sinoatrial Node / Q000378:metabolism* / Q000648:ultrastructure; D014316:Tritium; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D018727:Muscarinic Antagonists; D010761:Phosphorus Radioisotopes; D011976:Receptors, Muscarinic; D010566:Virulence Factors, Bordetella; D014316:Tritium; D010095:Oxotremorine; D000244:Adenosine Diphosphate; D011813:Quinuclidinyl Benzilate; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins