Signaling Mechanisms for Insulin

Signaling Mechanisms for Insulin

Insulin appears to work without second messengers generated when a hormone binds to a receptor on the plasma membrane of its tissue cells, referred to as target cells.

A hormone stimulus typically produces one or more of the following changes:

1. Alters plasma membrane permeability or membrane potential , or both, by opening or closing ion channels.

2. Stimulates synthesis of proteins or regulatory molecules such as enzymes within the cell.

3. Activates or deactivates enzymes.

4. Induces secretory activity.

5. Stimulates mitosis.

The insulin receptor is a tyrosine kinase enzyme that is activated by autophosphorylation (addition of the phosphate complex ion to several of its own tyrosines ) when insulin binds. This activated insulin receptor provides docking sites for intracellular relay proteins that, in turn, initiate a series of protein phosphorylations that trigger specific cell responses.

The phosphorylated proteins begin the cascade that leads to increased glucose uptake by the cells in the body.

After glucose enters a target cell, insulin binding triggers enzymatic activities that:

1. Catalyzes the oxidation of glucose for ATP production.

2. Join glucose molecules together to form glycogen.

3. Convert glucose to fat (particularly in adipose tissue.)

Signals, whether neural, hormonal or both are important to homeostasis and your health.