Sandbox Reserved 1627: Difference between revisions

[[Image:Purple insulin.png|thumb|right|150px|Figure 2: Insulin molecule. [http://www.rcsb.org/structure/3I40 PDB 3I40]]]Insulin is a [http://en.wikipedia.org/wiki/Peptide_hormone peptide hormone] produced and secreted from the [http://en.wikipedia.org/wiki/Pancreatic_islets islets of Langerhans] of the pancreas in response to high blood glucose levels. Insulin is commonly considered the anabolic hormone of the body, and is the an important [http://en.wikipedia.org/wiki/Ligand ligand] in glucose homeostasis. The structure of insulin is a simple monomer composed of two peptide chains linked by an intermolecular disulfide bridge. The glucose receptor is inactive in the absence of insulin. When there is a surplus of glucose circulating in the blood stream, the production of insulin is upregulated and will bind to many insulin receptors. Upon activation, the receptor undergoes a structural [http://en.wikipedia.org/wiki/Conformational_change conformation change] from the inactive <scene name='83/832953/Simple_inactivated_receptor/3'>inverted V</scene> state to the active <scene name='83/832953/Ir_dimer_t_state/3'>T shape</scene> state. The activation and conformation change lead to downstream signaling by the phosphorylation of the [http://en.wikipedia.org/wiki/Insulin_receptor_substrate Insulin Receptor Substrate] (IRS), resulting in glucose intake. The transport of extracellular glucose into the cell allows it to be converted to [http://en.wikipedia.org/wiki/Glycogen glycogen] for storage and later usage.