Human dystroglycan: skeletal muscle cDNA, genomic structure, origin of tissue specific isoforms and chromosomal localization

Dystroglycan is a novel laminin binding component of the dystrophin-glycoprotein complex which provides a linkage between the subsarcolemmal cytoskeleton and the extracellular matrix. Here we report the cDNA and genomic structure of human dystroglycan. The human dystroglycan is encoded by a single gene (DAG1) mapped to chromosome 3 band p21. The coding sequence is organized into two exons, separated by a large intron. The predicted amino acid sequence of human and rabbit dystroglycan are 93% identical with predicted glycosylation sites being conserved. Human dystroglycan is expressed in a variety of fetal and adult tissues. Our data suggest that muscle and non-muscle isoforms of dystroglycan differ by carbohydrate moieties but not protein sequence