A truncated dystrophin lacking the C-terminal domains is localized at the muscle membrane.

A Duchenne muscular dystrophy patient who displayed near-normal dystrophin staining at the sarcolemma with N-terminal, but not with C-terminal, anti-dystrophin monoclonal antibodies was found to have a frameshift deletion of exons 42 and 43. This deletion introduces an early termination codon, and a 225-kD protein was detected by western blotting with N-terminal antibodies only. The results suggest that an N-terminal truncated dystrophin fragment encoded by exon 1-41 is able to associate with the muscle cell membrane. The current idea that the C-terminal domains of dystrophin are important or essential for its integration with the sarcolemma may have to be reexamined in the light of these observations.