Expression of myotonic dystrophy protein kinase in biopsied muscles.

We present expression of myotonic dystrophy protein kinase (DM-PK) on biopsied muscles by immunocytochemistry using antibody against synthetic DM-PK peptide antigen. Immunolocalization of DM-PK was observed in neuromuscular junctions, muscle spindle, and sarcoplasm on both normal and DM muscles. DM-PK expression of sarcoplasm was present in adult normal and DM muscles. In Duchenne and Becker muscular dystrophies, DM-PK was intensively expressed in cytoplasm on immature regenerating fibers. DM-PK is initially produced in cytoplasm of regenerating fibers and migrates toward sarcoplasm with maturity of muscle cell.