Insulin receptor structure and function in normal and pathological conditions.

The insulin receptor is a large cell surface glycoprotein that concentrates insulin at the site of action and also initiates responses to insulin. The receptor is a disulfide-linked oligomer comprised of two alpha and two beta subunits. Signal transduction through the insulin receptor appears to require the activation of an intrinsic tyrosine-specific protein kinase activity. A variety of disorders, both acquired and genetic, are associated with the development of insulin resistance and are frequently the result of cellular defects in insulin receptor structure, function, and action. The recent cloning of several mutant receptors from patients with genetic forms of extreme insulin resistance has increased our understanding of insulin resistance on the molecular level.