Insulin receptor targeting

Insulin is composed of two peptide chains covalently linked by disulfide bonds (Figures 5.17 and 6.35). This monomer of insulin is the active form that binds to receptors in target cells. However, in solution, insulin spontaneously forms dimers, which themselves aggregate to form hexamers. The surface of the insulin molecule that self-associates to form hexamers is also the surface that binds to insulin receptors in target cells. Thus, hexamers of insulin are inactive. 

Kido Y, Nakae J, Accili D (2001) Clinical review 125 the insulin receptor and its cellular targets. J Clin Endocrinol Metab 86 972-979... 

Although many cells in the body express the insulin receptor, its most important targets are skeletal muscle fibres, hepatocytes and adipocytes, where it often antagonizes the effects of... 

Although many cells in the body express the insulin receptor, its most important targets are skeletal muscle fibres, hepatocytes and adipocytes, where it often antagonizes the effects of glucagon (Table 8.1). The most potent known stimulus of pancreatic insulin release is an increase in blood glucose levels, often occurring after meal times. Insulin orchestrates a suitable metabolic response to the absorption of glucose and other nutrients in a number of ways ... 

ATP sensitive K channels. They lower down the blood sugar level in type 11 diabetics and non-diabetic individuals. They also decrease the elevated plasma free fatty acid levels. They also sensitize the target tissues to action of insulin by increasing the number of insulin receptors. 

Kido Y et al The insulin receptor and its cellular targets. 3 Clin Endocrinol Metab 2001 86 972. [PMID 11238471]... 

Insulin-like growth factor-1 (IGF-1) is a peptide, 7649 Da, with structural homology to proinsulin. It binds preferentially to IGF-1 receptors on the surface of target cells. It has a lower affinity for insulin receptors. The receptors for insulin and IGF-1 share some structural and functional homology. IGF-1 is produced in the liver and in other organs in response to growth hormone action. IGF-1 that reenters the circulation is bound to... 

---