Insulin affects the ability of Gi to be ADP-ribosylated but does not elicit its phosphorylation in intact hepatocytes.
Insulin inhibited the ability of activated pertussis toxin to catalyse the ADP-ribosylation of alpha-Gi in isolated plasma membranes in either the absence of added guanine nucleotides or in the presence of GTP. In contrast, when the non-hydrolysable GTP analogue guanylyl-5'-imido-diphosphate (p[NH]ppG) was added to ribosylation mixtures, to inhibit the action of pertussis toxin in catalysing the ADP-ribosylation of alpha-Gi, then the addition of insulin attenuated the action of p[NH]ppG causing an increase in alpha-Gi ribosylation. Pre treatment of intact hepatocytes with insulin had no effect on the subsequent ability of thiol-preactivated pertussis toxin to cause the ADP-ribosylation of alpha Gi using isolated membranes from such cells. The ability of p[NH]ppG to inhibit forskolin-stimulated adenylate cyclase activity was attenuated in the presence of insulin. Insulin did not cause the phosphorylation of alpha-Gi in either intact hepatocytes or in isolated membranes.
Pyne
N J
NJ
Department of Biochemistry, University of Glasgow, Scotland, U.K.
Heyworth
C M
CM
Balfour
N W
NW
Houslay
M D
MD
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D037361:Adenylate Cyclase Toxin; D000067956:Adenylyl Cyclase Inhibitors; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D037342:Pertussis Toxin; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D000067759:Receptor for Advanced Glycation End Products / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D037361:Adenylate Cyclase Toxin; D000067956:Adenylyl Cyclase Inhibitors; D007328:Insulin; D000067759:Receptor for Advanced Glycation End Products; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D000246:Adenosine Diphosphate Ribose; D006165:Guanylyl Imidodiphosphate; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins