Effects of lithium ion on ADP ribosylation of inhibitory GTP-binding protein by pertussis toxin, islet-activating protein.
Studies were made on the effects of Li+ on ADP ribosylation of inhibitory GTP-binding (Gi) protein by islet-activating protein (IAP), pertussis toxin. The ADP ribosylation of 40-41 kDa proteins of the membranes of rat cardiac ventricular cells by IAP was reduced by the addition of a nonhydrolyzable analog of guanine nucleotide, GTP gamma S, indicating that these proteins included Gi protein. The addition of LiCl (0.5-10 mM) to the membrane fractions of the cells attenuated the ADP ribosylation of the Gi protein of the cell membranes by IAP dose-dependently. The effects of LiCl were reversible. Of the monovalent ions tested, Li+ inhibited the ADP ribosylation of the protein by IAP most strongly. The effects of LiCl (2 mM) were observed even in the presence of 150 mM KCl. Moreover, LiCl decreased the ADP ribosylation of purified Gi protein by IAP. These results support that Gi proteins are one of the targets for the therapeutic effects of lithium.
Kawamoto
H
H
Department of Medicine I, Hyogo College of Medicine, Japan.
Watanabe
Y
Y
Imaizumi
T
T
Iwasaki
T
T
Yoshida
H
H
D000244:Adenosine Diphosphate / Q000378:metabolism*; D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D066298:In Vitro Techniques; D008094:Lithium / Q000494:pharmacology*; D008566:Membranes / Q000187:drug effects / Q000378:metabolism; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D037342:Pertussis Toxin; D011188:Potassium / Q000378:metabolism; D051381:Rats; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D010566:Virulence Factors, Bordetella; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000244:Adenosine Diphosphate; D008094:Lithium; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D011188:Potassium