The Role of Insulin in Regulating Blood Sugar Levels and Glucose Homeostasis

A protein hormone synthesized in the pancreas that regulates blood sugar levelsActivates phosphoprotein phosphatase PP1Secreted in response to high blood glucoseIndirectly leads to dephosphorylation of bifunctional enzyme (activates PFK-2)

The protein hormone synthesized in the pancreas that regulates blood sugar levels is called insulin

The protein hormone synthesized in the pancreas that regulates blood sugar levels is called insulin. Insulin plays a crucial role in maintaining glucose homeostasis in the body.

Insulin is produced by beta cells in the pancreas and is released into the bloodstream in response to high blood glucose levels. When blood glucose levels rise, such as after a meal, insulin is secreted to facilitate the uptake and utilization of glucose by different tissues and organs in the body.

One of the main functions of insulin is to activate phosphoprotein phosphatase PP1. This enzyme is responsible for dephosphorylating various target proteins in the body. When insulin activates PP1, it indirectly leads to the dephosphorylation of a bifunctional enzyme.

This bifunctional enzyme, called phosphofructokinase-2 (PFK-2), has two different activities. One activity promotes the synthesis of fructose-2,6-bisphosphate (F-2,6-BP), which is a potent activator of glycolysis (the breakdown of glucose). The other activity inhibits gluconeogenesis (the production of glucose from non-carbohydrate sources).

When insulin triggers the dephosphorylation of the bifunctional enzyme, it activates the PFK-2 activity and inhibits the gluconeogenesis activity. This results in increased levels of F-2,6-BP, which facilitates the activation of glycolysis. As a result, glucose is efficiently metabolized for energy production or stored as glycogen in the liver and muscles.

Overall, the release of insulin in response to high blood glucose levels leads to the activation of phosphoprotein phosphatase PP1, which indirectly affects the dephosphorylation state of the bifunctional enzyme, activating PFK-2 and promoting glycolysis. This hormonal regulation ultimately helps to regulate blood sugar levels and maintain glucose homeostasis in the body.

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