Dystrophin and dystrophin-related protein expression in Torpedo marmorata electric organ.

The presence of different dystrophin-related protein forms was investigated in electric organ as compared to cardiac, white or red skeletal muscles from Torpedo marmorata. Two strategies were followed. First, we used specific C-terminal dystrophin and dystrophin-related protein monoclonal antibodies which we characterized in the present study. 400 kDa protein bands were detected in the tissues mentioned above with both specific types of antibodies. Second, we produced monoclonal antibodies raised against a dystrophin-enriched preparation from T. marmorata electric organ. Western blot and immunofluorescence analyses showed the tissue specificity of T. marmorata antibodies and allowed us to classify them as types I, II and III. Vessel walls and neuromuscular junctions were labeled with T. marmorata type II and III antibodies in human muscles (skeletal and smooth). Both approaches demonstrated that the T. marmorata electric organ contained different proteins related with dystrophin: a dystrophin form, a dystrophin-related protein form and a dystrophin-related protein isoform, homologous to the dystrophin-related protein present in muscle vessel walls and at the neuromuscular junctions of human tissues. The presence of dystrophin and dystrophin-related protein is finally discussed relative to their functions and organ specificities.