The different C termini of DMPK that arise from alternative splicing determine its localization to the endoplasmic reticulum, mitochondria, or cytosol in transfected COS-1 cells.

[10] Among the substrates for DMPK proposed by in vitro studies are phospholemman, the dihydropyridine receptor, and the myosin phosphatase targeting subunit.

[7] Although the specific function of this protein is unknown, it appears to play an important role in muscle, heart, and brain cells.

Affected individuals display a wide range of symptoms including myotonia, skeletal muscle weakness and wasting, cardiac conduction abnormalities, and cataracts.

Although DMPK lacks obvious binding sites for known G, DMPK-1 oligomers exhibit low basal catalytic activity due to the presence of the C-terminal autoinhibitory domain (AI).

The persistent activation of serine/threonine kinases has been shown to play a role in the determination of cell fate as well as memory production in the nervous system.

Thus, this model suggests that the two endogenous DMPK forms may possess different activities, localizations, regulators, and substrates and perform distinct physiological functions.