Structure
The Dystrophin-Glycoprotein Complex (DGC) is named for its glycosylated substituents of the main dystrophin protein. The molecule in its entirety is depicted . Dystrophin, the largest component of the total complex, is depicted in blue. One of the most obvious components of dystrophin's structure is its abundance of alpha helices, highlighted in pink. One of the glycosylated substituents is β-dystroglycan, which is a 15 polypeptide sequence depicted in green.
DGC can be further broken down into three unique subcomplexes. The dystroglycan complex contains both α- and β-dystroglycan molecules. The sarcoglycan complex contains dystrophin-associated glycoproteins. The dystrophin/dystrobrevin/syntrophin complex contains dystrophin-associated proteins.
Function
Dystrophin is a protein found in the muscle cell. It works to link actin filaments to another protein in the sarcolemma of the muscle's plasma membrane. The protein inside the sarcolemma connects the dystrophin to even more connective proteins to make three total linking proteins. This combination of proteins--with dystrophin playing the most important role-- supports the strength, stability, and overall function of the muscle. If dystrophin is not present, the muscle will become stiff and possibly deformed or at least at an increased risk of injury.
Diseases
Defects in the Dystrophin gene are the cause of Duchenne and Becker Muscular Dystrophies (DMD). Muscles that suffer from DMD are significantly low in dystrophin-associated glycoproteins. DMD is characterized by muscle weakness in the hips, pelvic region, and shoulders that lead to skeletal muscle swelling and enlargement. The prime cause of lethality of DMD is when the heart and respiratory muscles lose function. Becker Muscular Dystrophy is a mild version of DMD, spreading slower.
