Abstract
Dystrophin-associated glycoproteins (DAGs) have recently been classified into two groups by biochemical methods. One group, referred to as dystroglycan complex, is composed of 156DAG and 43DAG, while the other group, sarcoglycan complex, is composed of 50DAG, A3b, and 35 DAG. Each one protein belonging to these complexes was used as a marker for a tissue distribution study. 43DAG was present in all of the tissues examined, whereas 50DAG was present only in skeletal and cardiac muscles. In the muscles of Duchenne muscular dystrophy patients, which lack dystrophin, immunohistochemical staining using anti-DAGs antibodies revealed that 43DAG was well preserved, but that 50DAG, A3b, and 35DAG were greatly reduced. In the muscles of severe childhood autosomal recessive muscular dystrophy patients, in which dystrophin is present, almost all sarcoglycan complex was lost, although 43DAG was present like in control muscle. These findings suggest that dystroglycan and sarcoglycan complexes may play functionally different roles and that muscle degeneration and necrosis may be related to great reduction of sarcoglycan complex.
