Horm Metab Res 1998; 30(3): 113-117
DOI: 10.1055/s-2007-978847
Originals Basic

© Georg Thieme Verlag Stuttgart · New York

Insulin Antagonism: A Novel Role for Human Serum Transferrin

L. Vargas1 , M. E. Kawada1 , S. Bazaes1 , P. A. Karplus2 , C. H. Faerman2
  • 1Department of Cell and Molecular Biology, Pontifical Catholic University of Chile, Santiago, Chile
  • 2Section of Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, N. Y., U.S.A.
Further Information

Publication History

1997

1997

Publication Date:
20 April 2007 (online)

We have purified α2-glycoprotein (α2-GP), an insulin antagonist from human plasma which is induced by growth hormone (GH), and shown that pure α2-GP is a potent antagonist of severe insulin-induced hypoglycemia, producing acute hyperglycemia in intact rats and ketonuria in diabetic rats. The N-terminal amino acid sequence of α2-GP and the reactivity of α2-GP with an antitransferrin monoclonal antibody show that α2-GP is identical to human serum transferrin. Furthermore, pure human serum transferrin and non-glycosylated recombinant human transferrin reproduce the insulin antagonist effects of α2-GP in rats, whereas ovotransferrin shows no such effect. The neutralization of the insulin antagonism of human serum transferrin by an anti-transferrin monoclonal antibody shows that transferrin has a new function as a potent insulin antagonist. This novel role for human serum transferrin in the regulation of glucose metabolism provides a reasonable mechanism for the diabetogenic effect of GH, and has important implications for the etiology and progression of diabetes.