Explain the Role in Insulin Formation?

You are aware that insulin receptors are present in many cells with their concentration being highest in adipocytes (cells present in adipose tissue) and hepatocytes (liver cells). You also know that insulin receptor has two extracellular alpha-subunits and two extracellular beta-subunits. It is the alpha-subunit to which insulin binds. Once insulin binds to the alpha-subunit of the receptor, a specific phosphorylation of the beta-subunit occurs through a cascade of phosphorylation reactions. This leads to increased insulin sensitivity. The enzyme partly responsible for this phosphorylation is the 'insulin receptor tyrosine kinase'. This enzyme is activated by chromium. In rats, removal of chromium has been shown to result in the loss of kinase-potentiating activity. Besides activating the kinase, chromium also inhibits phosphotyrosine phosphatase-an enzyme responsible for inactivation of insulin receptor. The activation of 'insulin receptor tyrosine kinase and inhibition of 'insulin receptor tyrosine phosphatise by chromium would lead to an increased phosphorylation of the insulin receptor, which is associated with increased insulin sensitivity.