The stoichiometry, cellular location, glycosylation, and hydrophobic properties of the components in the dystrophin-glycoprotein complex were examined. The 156, 59, 50, 43, and 35 kd dystrophin-associated proteins each possess unique antigenic determinants, enrich quantitatively with dystrophin, and were localized to the skeletal muscle sarcolemma. The 156, 50, 43, and 35 kd dystrophin-associated proteins contained Asn-linked oligosaccharides. The 156 kd dystrophin-associated glycoprotein contained terminally sialylated Ser/Thr-linked oligosaccharides. Dystrophin, the 156 kd, and the 59 kd dystrophin-associated proteins were found to be peripheral membrane proteins, while the 50 kd, 43 kd, and 35 kd dystrophin-associated glycoproteins and the 25 kd dystrophin-associated protein were confirmed as integral membrane proteins. These results demonstrate that dystrophin and its 59 kd associated protein are cytoskeletal elements that are tightly linked to a 156 kd extracellular glycoprotein by way of a complex of transmembrane proteins.
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We gratefully acknowledge Steven Kahl, Suzanne Northrup, Kristin Stang, and Joseph Snook for expert technical assistance and thank Dr. Kay Ohlendieck for providing the sarcolemmal membranes used in this study. We also thank Dr. Frank Walsh for providing the NCAM antibody used in this study. K. P. C. is an investigator of the Howard Hughes Medical Institute. J. M. E. is the Carl M. Pearson Fellow of the Muscular Dystrophy Association. This work was also supported by a grant from the Muscular Dystrophy Association.
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