Co-localization of Dystrophin and β-Dystroglycan Demonstrated in En Face View by Double Immunogold Labeling of Freeze-fractured Skeletal Muscle

SUMMARY An absence of dystrophin causes Duchenne muscular dystrophy, but the precise mechanism underlying necrosis of the muscle cells is still unclear. Dystrophin and β-dystroglycan are components of a complex of at least nine proteins, the dystrophin-glycoprotein complex (DGC), that links the membrane cytoskeleton to extracellular elements in skeletal and cardiac muscle. Biochemical studies indicate that dystrophin is bound to other components of the DGC via β-dystroglycan, which suggests that the distribution of these two proteins should be almost identical. In this study, therefore, we examined the spatial relationship between dystrophin and β-dystroglycan with a range of different imaging techniques to investigate the extent of the predicted co-localization. We used (a) double immunogold fracture-label, a freeze-fracture cytochemical technique that allows high-resolution face-on views of labeled membrane components in thin sections and in platinum-carbon replicas, (b) double immunogold labeling of cr...