The insulin signaling pathway is essential in regulating the concentration of glucose in the blood following a meal rich in carbohydrates. The pathway involves many steps and molecules and failure of any step in the pathway can have severe consequences such as diabetes.
Our bodies digest the food we eat into amino acids sugars and fatty acids but how did the digested sugars get into our cells so they can be used for energy the pancreas releases the hormone insulin following ingestion of a meal containing carbohydrates insulin regulates the concentration of blood glucose the product of carbohydrate metabolism in most individuals
Insulin binds to a specific receptor on the plasma membrane of cells we will be focusing on skeletal muscle and adipose tissue cells the interaction between insulin and its receptor travels to the interior of the cell where it triggers a number of changes in cell metabolism including glucose uptake by cells in response to elevated blood glucose levels this process
Is known as the insulin signaling pathway the insulin receptor is a dimer made of two extracellular alpha subunits and two transmembrane beta subunits disulfide bonds connect the alpha and beta subunits as well as the two alpha subunits to maintain the receptor as a dimer now we’re going to go through the initial steps of the insulin signaling pathway insulin binds
To the alpha subunits of the insulin receptor which face the extracellular environment this interaction translates to the beta subunits which have tyrosine kinase domains that become activated to phosphorylate each other and other proteins irs-1 binds to the phosphorylated tyrosine residues which then results in the phosphorylation of irs-1 the phosphorylated sites
On irs-1 serve as binding sites for the pi3 kinase pi3 kinase phosphorylates pip2 a membrane phospholipid the addition of the phosphate converts pib to two pip3 which serves as a recognition site for the pip3 dependent protein kinase or pd k1 for short pd k1 phosphorylates a kt another protein kinase which further relays the signal to the interior of the cell
This cascade involves many subsequent steps and proteins not shown here in tissues such as skeletal muscle and adipose tissue all these steps eventually lead to the recruitment of additional glucose transporters from storage and intracellular vesicles to the plasma membrane in order to facilitate glucose transport into cells glucose transporters are transmembrane
Channel proteins that allow glucose to travel from outside the cell to inside decreasing blood glucose levels skeletal muscle and adipose tissue contain glucose transporters once glucose enters cells it is metabolized further to generate atp and used to synthesize molecules of glycogen which are stored and skeletal muscle and liver tissues or fatty acids stored in
Adipose tissue failure to regulate blood glucose can result in diabetes type 1 or insulin dependent diabetes can result from failure of the pancreas to produce insulin in this complex metabolic autoimmune disease the immune system attacks the beta cells of the pancreas which normally produce insulin as a result insulin synthesis is prevented type 2 diabetes occurs
When insulin receptors no longer respond to insulin resulting in elevated blood glucose levels among other symptoms as you can see the insulin signaling pathway is essential and regulating the concentration of glucose in the blood following a meal rich in carbohydrates the pathway involves many steps and molecules and failure of any step in the pathway can have
Severe consequences such as diabetes you
Transcribed from video
The Insulin Signaling Pathway By Mary Accurso
