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Insulin Resistance And Muscle Insulin Receptor Substrate-1 Serine Hyperphosphorylation, Charles A. Stuart, Mary E. A. Howell, Brian M. Cartwright, Melanie P. Mccurry, Michelle L. Lee, Michael W. Ramsey, Michael H. Stone

ETSU Faculty Works

Insulin resistance in metabolic syndrome subjects is profound in spite of muscle insulin receptor and insulin-responsive glucose transporter (GLUT4) expression being nearly normal. Insulin receptor tyrosine kinase phosphorylation of insulin receptor substrate-1 (IRS-1) at Tyr896 is a necessary step in insulin stimulation of translocation of GLUT4 to the cell surface. Serine phosphorylation of IRS-1 by some kinases diminishes insulin action in mice. We evaluated the phosphorylation status of muscle IRS-1 in 33 subjects with the metabolic syndrome and seventeen lean controls. Each underwent euglycemic insulin clamps and a thigh muscle biopsy before and after 8 weeks of either strength or …