Costamere

The costamere is a structural-functional component of skeletal muscle cells which, according to original descriptions in the early 1980s (which are generally still accepted), are sub-sarcolemmal protein assemblies circumferentially aligned in register with the Z-disk of peripheral myofibrils. They physically couple force-generating sarcomeres with the sarcolemma in striated muscle cells and are thus considered the "Achilles heel", i.e. the key vulnerable point of the muscle which are defective in many myopathies

The costamere is also known as the dystrophin-associated protein complex (DAPC) as well as the dystroglycan complex, due to the presence of the proteins that are enriched there.