response to insulin

Definition

Target type: biologicalprocess

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of an insulin stimulus. Insulin is a polypeptide hormone produced by the islets of Langerhans of the pancreas in mammals, and by the homologous organs of other organisms. [GOC:mah, ISBN:0198506732]

Insulin, a peptide hormone produced by the beta cells of the pancreas, plays a crucial role in regulating blood glucose levels. When blood glucose levels rise after a meal, insulin is released and binds to its receptor on target cells, primarily muscle, liver, and fat cells. This binding activates a cascade of intracellular signaling events, leading to the uptake and utilization of glucose.

Insulin signaling begins with the binding of insulin to its receptor, a tyrosine kinase receptor located on the cell surface. This binding triggers a series of phosphorylation events, activating downstream signaling molecules such as the insulin receptor substrate (IRS) proteins. Activated IRS proteins then activate the phosphatidylinositol 3-kinase (PI3K) pathway, leading to the activation of the protein kinase B (Akt) pathway.

Akt plays a central role in insulin signaling, promoting glucose uptake, glycogen synthesis, and protein synthesis. It also inhibits gluconeogenesis, the production of glucose from non-carbohydrate sources, further reducing blood glucose levels.

1. **Glucose uptake:** Insulin stimulates glucose uptake into muscle and fat cells by promoting the translocation of glucose transporter 4 (GLUT4) from intracellular vesicles to the cell membrane. GLUT4 is a glucose transporter that facilitates the diffusion of glucose into the cell.

2. **Glycogen synthesis:** Insulin activates glycogen synthase, the enzyme responsible for the synthesis of glycogen, a storage form of glucose. This process stores excess glucose in the liver and muscle cells, preventing hyperglycemia.

3. **Protein synthesis:** Insulin promotes protein synthesis by increasing the translation of mRNA into protein. This is important for growth and repair of tissues.

4. **Inhibition of gluconeogenesis:** Insulin suppresses gluconeogenesis by inhibiting the activity of key enzymes involved in this process, such as phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase. This reduces the production of glucose from non-carbohydrate sources, further contributing to the lowering of blood glucose levels.

In summary, insulin signaling is a complex process that involves multiple signaling pathways and downstream targets. This intricate regulation ensures proper glucose homeostasis, preventing both hypoglycemia and hyperglycemia, and maintaining optimal metabolic function.
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Proteins (27)

Compounds (939)