Primary structure of dystrophin-associated glycoproteins linking dystrophin to the extracellular matrix.

The primary sequence of two components of the dystrophin-glycoprotein complex has been established by complementary, DNA cloning. The transmembrane 43K and extracellular 156K dystrophin-associated glycoproteins (DAGs) are encoded by a single messenger RNA and the extracellular 156K DAG binds laminin. Thus, the 156K DAG is a new laminin-binding glycoprotein which may provide a linkage between the sarcolemma and extracellular matrix. These results support the hypothesis that the dramatic reduction in the 156K DAG in Duchenne muscular dystrophy leads to a loss of a linkage between the sarcolemma and extracellular matrix and that this may render muscle fibres more susceptible to necrosis.