glucose import in response to insulin stimulus

Definition

Target type: biologicalprocess

The directed movement of the hexose monosaccharide glucose into a cell as a result of an insulin stimulus. [GOC:BHF, PMID:19079291]

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, a transmembrane protein found on the surface of cells, primarily in skeletal muscle, adipose tissue, and the liver. This binding initiates a signaling cascade that ultimately leads to increased glucose uptake by these tissues.

The insulin receptor is a tyrosine kinase receptor, meaning it possesses intrinsic enzymatic activity that phosphorylates tyrosine residues on intracellular proteins. Upon insulin binding, the receptor undergoes autophosphorylation, activating its tyrosine kinase activity. This, in turn, activates a series of intracellular signaling molecules, including the insulin receptor substrate (IRS) proteins.

IRS proteins are adaptor molecules that bridge the insulin receptor to downstream signaling pathways. They are phosphorylated by the activated receptor, creating docking sites for other signaling proteins. One key pathway activated by IRS proteins involves the phosphoinositide 3-kinase (PI3K) pathway.

PI3K phosphorylates phosphatidylinositol (PIP2) to form phosphatidylinositol-3,4,5-trisphosphate (PIP3). PIP3 acts as a signaling molecule, recruiting and activating the protein kinase Akt (also known as protein kinase B). Akt plays a crucial role in glucose transport by phosphorylating and inactivating a protein called glycogen synthase kinase 3 (GSK3).

GSK3 normally inhibits the translocation of glucose transporter 4 (GLUT4) to the cell surface. GLUT4 is the main glucose transporter responsible for insulin-stimulated glucose uptake in skeletal muscle, adipose tissue, and the liver. By inhibiting GSK3, Akt promotes the translocation of GLUT4 from intracellular vesicles to the plasma membrane.

This translocation increases the number of GLUT4 transporters on the cell surface, effectively increasing the capacity for glucose uptake. As glucose enters the cell, it is either utilized for immediate energy production or stored as glycogen. Insulin also stimulates the synthesis of glycogen, further contributing to the regulation of blood glucose levels.

In summary, insulin binding to its receptor triggers a signaling cascade that ultimately leads to increased glucose uptake through the activation of the PI3K pathway and the translocation of GLUT4 to the cell surface. This process effectively lowers blood glucose levels, maintaining metabolic homeostasis.'
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Proteins (1)

Compounds (2)