Localization of dystrophin COOH-terminal domain by the fracture-label technique.

The precise localization of dystrophin in the skeletal muscle cell should contribute to a better understanding of the yet unclear functional role of this protein, both in normal and in Duchenne muscular dystrophy. Immunocytochemical studies did not give conclusive results on the localization of dystrophin with respect to the sarcolemma and to the cytoskeletal components. To improve the reliability of the electron microscopic immunocytochemical localization of dystrophin, a mAb against the COOH-terminus of the molecule has been used in association with the fracture-label technique, which, causing a partition of the membrane in protoplasmic and exoplasmic halves, allows a more precise dystrophin localization. The results obtained indicate that dystrophin is associated with the protoplasmic half of the plasmalemma, and the observation that it does not randomly follow the partition of the membrane is consistent with a stable association with the cytoskeleton.