Pertussis toxin catalyzed ADP-ribosylation of a 41 kDa G-protein impairs insulin-stimulated glucose metabolism in BC3H-1 myocytes.
In this study, we examined the effects of pertussis toxin (PT) on the ADP-ribosylation of guanine nucleotide binding proteins (G-proteins) and various insulin-stimulated processes in cultured BC3H-1 myocytes. Treatment of intact myocytes with 0.1 microgram/ml PT for 24 hours resulted in the complete ribosylation of a 41 kDa protein. The 41 kDa PT substrate was immunoprecipitated with antibodies directed against a synthetic peptide corresponding to a unique sequence in the alpha subunit of Gi-proteins. PT treatment of intact cells had no effect on insulin receptor binding or internalization. However, PT inhibited insulin-stimulated glucose transport at all insulin-concentrations tested (1-100 ng/ml). Maximally stimulated glucose transport was reduced by 50% +/- 15%. Insulin-stimulated glucose oxidation was also decreased by 31% +/- 8%. The toxin had no significant effect on the basal rates of glucose transport and glucose oxidation. The time course of PT-induced inhibition on glucose transport correlated with the time course of the "in vivo" ADP-ribosylation of the 41 kDa protein. The results suggest that a 41 kDa PT-sensitive G-protein, identical or very similar to Gi, is involved in the regulation of glucose metabolism by insulin in BC3H-1 cells.
Moises
R S
RS
Department of Medicine, University of California, San Diego, La Jolla 92093.
Heidenreich
K A
KA
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D019204:GTP-Binding Proteins / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism* / Q000493:pharmacokinetics; D007328:Insulin / Q000494:pharmacology*; D051379:Mice; D009132:Muscles / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D010084:Oxidation-Reduction; D037342:Pertussis Toxin; D011972:Receptor, Insulin / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D007328:Insulin; D010566:Virulence Factors, Bordetella; D000246:Adenosine Diphosphate Ribose; D037342:Pertussis Toxin; D011972:Receptor, Insulin; D019204:GTP-Binding Proteins; D005947:Glucose