Effects of phosphorylation of inhibitory GTP-binding protein by cyclic AMP-dependent protein kinase on its ADP-ribosylation by pertussis toxin, islet-activating protein.
Pretreatment of rat cardiac myocytes with the beta-adrenergic agonist, db-cAMP or forskolin decreased ADP-ribosylation of 40-41 kDa protein by islet-activating protein (IAP) in cell membranes. Addition of activated cyclic AMP-dependent protein kinase (protein kinase A) catalytic subunit and MgCl2 also decreased ADP-ribosylation of 40-41 kDa protein by IAP in cell membranes. The alpha- and beta-subunits of partially purified inhibitory GTP-binding protein (Gi) were both phosphorylated by protein kinase A. The amounts of phosphate incorporated into the subunits of Gi were 0.34 and 0.18 mol/mol protein. These show that phosphorylation of Gi by protein kinase A results in a decrease in its ADP-ribosylation by IAP.
Watanabe
Y
Y
Department of Pharmacology I, Osaka University, School of Medicine, Japan.
Imaizumi
T
T
Misaki
N
N
Iwakura
K
K
Yoshida
H
H
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D000242:Cyclic AMP / Q000502:physiology; D019204:GTP-Binding Proteins / Q000502:physiology*; D066298:In Vitro Techniques; D009206:Myocardium / Q000378:metabolism; D037342:Pertussis Toxin; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D013329:Structure-Activity Relationship; D010566:Virulence Factors, Bordetella / Q000378:metabolism*
D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D000242:Cyclic AMP; D037342:Pertussis Toxin; D011494:Protein Kinases; D019204:GTP-Binding Proteins