Dystrophin-associated protein complex

Dystrophin-associated protein complex (DAPC) is a group of proteins that work together to maintain the integrity and stability of muscle fiber cells. The DAPC is crucial for the proper functioning of muscle cells, and mutations in the genes encoding these proteins can lead to various forms of muscular dystrophy.

Structure

The DAPC is composed of several proteins, including dystrophin, sarcoglycans, dystroglycans, and syntrophins. These proteins interact with each other to form a complex that links the cytoskeleton of the muscle fiber to the surrounding extracellular matrix.

Dystrophin is the central component of the DAPC. It is a large protein that binds to actin filaments in the cytoskeleton and to dystroglycans in the membrane of the muscle fiber. Dystroglycans, in turn, bind to laminin in the extracellular matrix. This connection between the cytoskeleton and the extracellular matrix helps to stabilize the muscle fiber and protect it from damage during muscle contraction.

Sarcoglycans are a group of proteins that form a subcomplex within the DAPC. They are located in the membrane of the muscle fiber and interact with both dystrophin and dystroglycans. Syntrophins are another group of proteins in the DAPC. They bind to dystrophin and serve as a link between the DAPC and other signaling proteins in the muscle fiber.

Function

The main function of the DAPC is to provide structural support to muscle fibers. By linking the cytoskeleton of the muscle fiber to the extracellular matrix, the DAPC helps to maintain the shape and integrity of the muscle fiber. This is particularly important during muscle contraction, when the muscle fiber is subjected to mechanical stress.

In addition to its structural role, the DAPC is also involved in signaling pathways that regulate muscle growth and repair. For example, the DAPC has been shown to interact with nitric oxide synthase, an enzyme that produces nitric oxide, a molecule that plays a key role in muscle regeneration.

Clinical significance

Mutations in the genes encoding the proteins of the DAPC can lead to various forms of muscular dystrophy, a group of genetic disorders characterized by progressive muscle weakness and degeneration. The most common of these is Duchenne muscular dystrophy, which is caused by mutations in the dystrophin gene. Other forms of muscular dystrophy, such as limb-girdle muscular dystrophy and Becker muscular dystrophy, are caused by mutations in the genes encoding sarcoglycans and other components of the DAPC.

See also

• Muscular dystrophy
• Dystrophin
• Sarcoglycan
• Dystroglycan
• Syntrophin