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. Therefore, we hypothesize that variable glycosylation of the conserved protein core might modulate laminin binding. The relationship of dystroglycan to human diseases is discussed.
Ibraghimov-Beskrovnaya
O
O
Howard Hughes Medical Institute, University of Iowa College of Medicine, Iowa City 52242.
Milatovich
A
A
Ozcelik
T
T
Yang
B
B
Koepnick
K
K
Francke
U
U
Campbell
K P
KP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002874:Chromosome Mapping; D002893:Chromosomes, Human, Pair 3; D003598:Cytoskeletal Proteins / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics*; D049030:Dystroglycans; D005796:Genes; D006801:Humans; D008322:Mammals / Q000235:genetics; D008562:Membrane Glycoproteins; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics*; D009132:Muscles / Q000737:chemistry*; D009928:Organ Specificity; D011817:Rabbits / Q000235:genetics; D016415:Sequence Alignment; D013045:Species Specificity
D003598:Cytoskeletal Proteins; C483081:DAG1 protein, human; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D009124:Muscle Proteins; D049030:Dystroglycans