Sarcospan, discovered by the research group of Kevin Campbell

Kevin Campbell (scientist)

Kevin P. Campbell, Ph.D. is an Investigator for the Howard Hughes Medical Institute, UI Foundation Distinguished Professor, the Roy J. Carver Chair of Molecular Physiology and Biophysics, and head of the department; he is also professor of neurology and internal medicine at the University of Iowa.-...

, is a 25-kDa transmembrane protein

Transmembrane protein

A transmembrane protein is a protein that goes from one side of a membrane through to the other side of the membrane. Many TPs function as gateways or "loading docks" to deny or permit the transport of specific substances across the biological membrane, to get into the cell, or out of the cell as...

 located in the dystrophin-associated protein complex

Dystrophin-associated protein complex

The dystrophin-associated protein complex is a multiprotein complex that includes dystrophin and the dystrophin-associated proteins.Many forms of muscular dystrophy are associated with disorders of the dystrophin-associated protein complex....

 of skeletal muscle

Skeletal muscle

Skeletal muscle is a form of striated muscle tissue existing under control of the somatic nervous system- i.e. it is voluntarily controlled. It is one of three major muscle types, the others being cardiac and smooth muscle...

 cells. It contains four transmembrane spanning helices with both N- and C-terminal domains located intracellularly. Loss of sarcospan expression occurs in patients with Duchenne muscular dystrophy

Duchenne muscular dystrophy

Duchenne muscular dystrophy is a recessive X-linked form of muscular dystrophy, which results in muscle degeneration, difficulty walking, breathing, and death. The incidence is 1 in 3,000 boys. Females and males are affected, though females are rarely affected and are more often carriers...

, indicating that dystrophin

Dystrophin

Dystrophin is a rod-shaped cytoplasmic protein, and a vital part of a protein complex that connects the cytoskeleton of a muscle fiber to the surrounding extracellular matrix through the cell membrane. This complex is variously known as the costamere or the dystrophin-associated protein complex...

 is required for proper localization of sarcospan. Interestingly, sarcospan knockout mice exhibit normal muscle structure and function, indicating that sarcospan is not necessary for muscle to develop.