What happens to IRS-1 upon activation of insulin signaling?

Upon activation of insulin signaling, IRS-1 (Insulin Receptor Substrate-1) is phosphorylated. Insulin binds to its receptor, which is a receptor tyrosine kinase. This binding activates the receptor and triggers autophosphorylation, which subsequently phosphorylates downstream substrates, including IRS-1. The phosphorylation of IRS-1 is a critical step in insulin signaling, as it creates docking sites for various signaling proteins. This cascade ultimately leads to the metabolic effects of insulin, such as the uptake of glucose by cells.

The phosphorylation of IRS-1 activates signaling pathways that promote the effects of insulin, including glucose transport into cells, lipid synthesis, and glycogen synthesis, among others. This represents a vital mechanism by which insulin exerts its physiological roles in glucose homeostasis and metabolism.