[Localization of DM-PK in normal and myotonic dystrophy muscles]

Myotonic dystrophy (DM) is an autosomal-dominant, multi-system disorder characterized by myotonia, progressive muscleatrophy and weakness. DM is also associated with smooth muscle, cardiac muscle, lens, endocrine and central nervous system abnormalities. The phenotypic expression of DM varies from asymptomatic adults to severely affected neonates. The genetic basis for DM is the expansion of a CTG repeat in the 3' end of a transcript that encodes a protein with putative serine/threonine protein kinase (myotonic dystrophy protein kinase, DM-PK). The predicted molecular weight of the full-length human DM-PK is about 69 kDa, while it may have some isoforms. DM-PK expression is observed in neuromuscular junction, muscle spindle, and sarcoplasm on both normal and DM muscles. Other muscular dystrophies, such as Duchenne and Becker type, DM-PK is intensively expressed in cytoplasm on immature regenerating fibers.