Insulin

Insulin (5808 Da) is a peptide hormone composed of 51 amino acid residues. It is produced in the Islets of Langerhans in the pancreas. In beta cells, insulin is synthesized from the proinsulin precursor molecule by the action of proteolytic enzymes, known as prohormone convertases, as well as the exoprotease carboxypeptidase E. Insulin is used to treat some forms of diabetes mellitus.Its principal function is to control the uptake and utilisation of glucose in peripheral tissue via the glucose transporter. This and other hypoglycaemic activities, such as the inhibition of hepatic gluconeogenesis and glycogenolysis are counteracted by the hyperglycaemic hormones including glucagon, epinephrine (adrenaline), growth hormone and cortisol.