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Insulin Structure & Function

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{{STRUCTURE_2hiu | PDB=2hiu | SCENE= }}
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<StructureSection load='' size='500' side='right' scene='34/347648/Two_chains/1' caption='Human insulin chain A (grey) and chain B (green), [[2hiu]]'>
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==Function==
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'''Insulin''' is made by the pancreatic islet beta cells in response to elevated blood glucoselevels. Insulin signals cells that the body is in the "fed" state, and that it should take up glucose from the blood and make other appropriate response. For example, in the liver glycogen synthesis is turned on, which provides a supply of glucose when the blood glucose levels fall under fasting conditions. Insulin also increases fat synthesis in adipocytes. In type 1 diabetes, the pancreatic cells do not release insulin, resulting in high blood sugar levels and increased fat metabolism. Consequently, there is "spillover" of glucose into the urine, and weight loss due to the loss of body fat stores.
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==Structure==
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Insulin is composed of two different types of peptide chains. <scene name='34/347648/Chain_a/1'>Chain A</scene> has 21 amino acids and <scene name='34/347648/Chain_b/1'>Chain B</scene> has 30 amino acids. Both chains contain <scene name='34/347648/Secondary_structures/1'>alpha helices</scene> but no beta strands. There are 3 conserved <scene name='34/347648/Disulfide_bonds/1'>disulfide bridges</scene> which help keep the two chains together. Insulin can also form <scene name='User:Whitney_Stoppel/sandbox1/Insulin_dimer/2'>dimers</scene> in solution due to the hydrogen bonding between the B chains (shown as white lines). The dimers can further interact to form <scene name='User:Whitney_Stoppel/sandbox1/Insulin_hexamer/4'>hexamers</scene> due to interaction between hydrophobic surfaces. This <scene name='User:Whitney_Stoppel/sandbox1/Insulin_ph7/2'>scene highlights</scene> the hydrophobic (gray) and polar (purple) parts of an insulin monomer at a pH of 7.
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== INSULIN ==
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A number of insulin variants have been made to favor either the monomeric or hexameric form. Deletion of the <scene name='34/347648/Hexamer_bchaincterminus/2'>five C terminal residues of the B chain</scene> creates a monomer only form. This portion of the B chain is involved in <scene name='34/347648/Dimer_bchainctermhbond/1'>hydrogen bonds</scene> between the B chain of one monomer and the A (marked C) and B (marked D) chain of another monomer.
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</StructureSection>
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==3D structures of insulin==
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[[Insulin]]
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'''Function'''
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Insulin is located in the pancreas. It is made by the pancreatic islet cells. Insulin helps to regulate the blood glucose in the body. It converts the glucose into glycogen, storing it into the liver. The glycogen then converts the stored glycogen to glucose when the body is under fasting condition to provide energy. Insulin also helps to get rid of fatty acids. It slows the breakdown of triglycerides which leads to the reduction of fatty acids in the blood. When insulin is not able to produce from your body it causes your body to uses fatty acids for energy instead or carbohydrates.
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''
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Structure''
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Insulin is monomeric and is composed of two polypeptide chains. It is composed of two different types of peptide chains. Chain A has 21 amino acids and Chain B has 30 amino acids. Insulin has a three dimensional structure consisting of 3 helices and 3 conserved disulfide bridges. The molecules in insulin sometimes form dimers in solution due to the hydrogen bonding between the B chains. Granules consisting hexamers are also sometimes formed by insulin. This is caused by the intercation between hydrophobic surfaces.
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==Additional Resources==
==Additional Resources==
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Thanks to 'User:Whitney_Stoppel' for the hexameric insulin scenes.
For additional information, see: [[Diabetes & Hypoglycemia]]
For additional information, see: [[Diabetes & Hypoglycemia]]
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Current revision

Human insulin chain A (grey) and chain B (green), 2hiu

Drag the structure with the mouse to rotate

3D structures of insulin

Insulin

Additional Resources

Thanks to 'User:Whitney_Stoppel' for the hexameric insulin scenes. For additional information, see: Diabetes & Hypoglycemia

Proteopedia Page Contributors and Editors (what is this?)

Ann Taylor, Michal Harel, David Canner, Pat McQuaid

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