Myotonic dystrophy protein kinase phosphorylates phospholamban and regulates calcium uptake in cardiomyocyte sarcoplasmic reticulum.

Myotonic dystrophy (DM) is caused by a CTG expansion in the 3'-untranslated region of a protein kinase gene (DMPK). Cardiovascular disease is one of the most prevalent causes of death in DM patients. Electrophysiological studies in cardiac muscles from DM patients and from DMPK(-/-) mice suggested that DMPK is critical to the modulation of cardiac contractility and to the maintenance of proper cardiac conduction activity.