Insulin stimulates association of a 41kDa G-protein (GIR41) with the insulin receptor.
Insulin has a paradoxical effect on a 41kDa Gi-like protein: Although insulin-treatment of rat adipocytes inhibited pertussis toxin-catalyzed ADP-ribosylation of a 41kDa G-protein in membranes in a dose-dependent manner, it simultaneously increased ADP-ribosylation of a 41kDa G-protein that co-immunoprecipitates with the insulin receptor (GIR41). The latter effect was insulin concentration- and time-dependent. The dose-dependent stimulatory effect of insulin on the autophosphorylation of the insulin receptor and on the ADP-ribosylation of the GIR41 in the insulin receptor immunoprecipitates closely paralleled each other. The time course of insulin-stimulated increase in the ADP-ribosylated GIR41, although rapid, was slower than the autophosphorylation of the receptor. The GIR41 is associated with and regulated by the insulin receptor further supporting an important role for this G-protein in modulating insulin action at the receptor level.
Jo
H
H
Department of Pathology, University of Alabama at Birmingham 35294.
Byer
S
S
McDonald
J M
JM
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D019204:GTP-Binding Proteins / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D008566:Membranes / Q000378:metabolism; D011233:Precipitin Tests; D051381:Rats; D017207:Rats, Sprague-Dawley; D011972:Receptor, Insulin / Q000378:metabolism*
D007328:Insulin; D000246:Adenosine Diphosphate Ribose; D011972:Receptor, Insulin; D019204:GTP-Binding Proteins