Xp21 dystrophin and 6q dystrophin-related protein. Comparative immunolocalization using multiple antibodies

A protein of Mr 400 K and slightly lower Mr than Xp21 dystrophin was detected in skeletal muscle from patients with Duchenne muscular dystrophy by three antibodies raised against the midrod and C-terminal portions of chicken dystrophin, and by antibodies to dystrophin-related protein. Immunocytochemistry showed continuous sarcolemmal staining of Duchenne muscle with these antibodies. Subcellular localization to the inner face of the plasma membrane of Duchenne muscle was demonstrated by immunoelectron microscopy using the model of a Duchenne patient deleted for most of the dystrophin gene. Other antibodies were specific for Xp21 dystrophin. In conclusion, a dystrophin homologue that may be identical to the previously described dystrophin-related protein (DRP)1 is expressed in Duchenne muscle with intracellular distribution similar to Xp21 dystrophin in normal muscle.