Dystroglycan

Dystroglycan is a protein that in humans is encoded by the DAG1 gene. It is a central component of the dystrophin-glycoprotein complex (DGC), which connects the extracellular matrix and the cytoskeleton in skeletal muscle cells. This connection is crucial for the stability of the muscle fiber during contraction.

Structure

Dystroglycan is synthesized as a single precursor protein, which is then cleaved into two subunits. The larger, extracellular alpha-dystroglycan (α-DG) binds to laminin in the extracellular matrix. The smaller, transmembrane beta-dystroglycan (β-DG) binds to dystrophin, a cytoskeletal protein. The two subunits are non-covalently linked.

Function

The dystroglycan complex plays a key role in maintaining the structural integrity of skeletal muscles. It provides a mechanical link between the extracellular matrix and the cytoskeleton, which is necessary for the stability of the muscle fiber during contraction. Disruptions in this complex can lead to muscular dystrophies.

Clinical significance

Mutations in the DAG1 gene can cause a variety of congenital muscular dystrophies (CMDs), including Walker-Warburg syndrome (WWS), Muscle-eye-brain disease (MEB), and Fukuyama congenital muscular dystrophy (FCMD). These disorders are characterized by severe muscle weakness and developmental abnormalities in the brain and eyes.

See also

• Dystrophin
• Dystrophin-glycoprotein complex
• Congenital muscular dystrophies

References

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