Alpha-2-Macroglobulin

Alpha-2-Macroglobulin (A2M) is a large plasma protein found in the blood. It is produced by the liver and is a major component of the immune system. A2M is known for its ability to inhibit a wide range of proteases, which are enzymes that break down proteins. This protein is a crucial part of the body's defense mechanism against pathogens and is involved in various physiological processes, including fibrinolysis, the breakdown of fibrin in blood clots.

Structure

Alpha-2-Macroglobulin is a tetrameric protein, meaning it is composed of four identical subunits. Each subunit contains a bait region that can trap proteases. When a protease cleaves the bait region, A2M undergoes a conformational change that entraps the protease, rendering it inactive. This mechanism allows A2M to inhibit a broad spectrum of proteases, including serine proteases, cysteine proteases, and metalloproteases.

Function

Protease Inhibition

A2M acts as a "molecular trap" for proteases. It is a non-specific inhibitor, meaning it can inhibit a wide variety of proteases. This is important in regulating protease activity in the body, preventing excessive tissue damage and inflammation.

Role in Fibrinolysis

In the process of fibrinolysis, A2M plays a role by inhibiting proteases that degrade fibrin, a protein involved in blood clotting. This regulation is crucial for maintaining the balance between clot formation and dissolution, preventing excessive bleeding or thrombosis.

Clinical Significance

Alpha-2-Macroglobulin levels can be measured in the blood and are used as a marker for various diseases. Elevated levels of A2M are associated with liver disease, nephrotic syndrome, and diabetes mellitus. Conversely, decreased levels may indicate acute pancreatitis or prostate cancer.

Related Pages

• Protease
• Fibrinolysis
• Immune system
• Liver

Alpha-2-Macroglobulin

• 

  Fibrinolysis