Phosphorylation of Gi protein by cyclic AMP-dependent protein kinase inhibits its dissociation into alpha-subunits and beta gamma-subunits by Mg2+ and GTP gamma S.
Pretreatment of partially purified inhibitory GTP-binding protein (Gi, 41 kDa) with activated cyclic AMP-dependent protein kinase (PKA) decreases its ADP-ribosylation by islet-activating protein (pertussis toxin, IAP). We examined whether this decrease was associated with dissociation of the trimer of alpha beta gamma-subunits of Gi protein into alpha-subunits and beta gamma-subunits. Results showed that phosphorylation of the Gi protein by PKA impaired its dissociation into alpha-subunits and beta gamma-subunits by 50 mM Mg2+ and 100 microM GTP gamma S. The results suggested that phosphorylation of the Gi protein by PKA possibly caused a conformational change of the trimer Gi protein.
Imaizumi
T
T
Department of Pharmacology I, Osaka University, School of Medicine, Japan.
Watanabe
Y
Y
Yoshida
H
H
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology*; D009243:NAD / Q000378:metabolism; D037342:Pertussis Toxin; D010766:Phosphorylation; D011487:Protein Conformation; D011494:Protein Kinases / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D010566:Virulence Factors, Bordetella; D009243:NAD; D000246:Adenosine Diphosphate Ribose; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D037342:Pertussis Toxin; D011494:Protein Kinases; D019204:GTP-Binding Proteins; D008274:Magnesium