[Insulin receptor and diabetes]

Insulin receptor is a membrane-bound glycoprotein playing a key role in transmembrane signaling of insulin. Therefore, it is logical to look for abnormal structure or functions of this protein in insulin resistance syndromes, such as major insulin resistance syndromes and non insulin dependent diabetes mellitus. Cloning of the insulin receptor cDNA allowed to identify the functional domains of the protein (insulin binding site, autophosphorylation sites and tyrosine-kinase domain). Mutations of the insulin receptor gene are often observed in rare syndromes of major insulin resistance, such as leprechaunism, type A insulin resistance and Rabson-Mendenhall syndrome. However, such studies are disappointing in the case of NIDDM, in which defects of other proteins involved in insulin action should be investigated.