DMPK phosphorylates PLN

Stable Identifier
Reaction [transition]
Homo sapiens
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Force generation of the heart and calcium homeostasis are coupled in the myocardium. In the sarcoplasmic reticulum (SR), calcium stores provide the majority of calcium used in muscle contraction-relaxation. During relaxation, an ATP-dependent calcium pump (ATP2A2 aka SERCA) in the SR is essential for the recovery of calcium. The reuptake of calcium by ATP2A2 determines the rate of relaxation and the size of the calcium store available for subsequent contractions. In cardiac muscle, a second protein called phospholamban (PLN) acts as a reversible inhibitor of ATP2A2 and thereby modulates contractility in response to physiological factors. Defects in PLN are associated with lethal dilated cardiomyopathy in humans (Ceholski et al. 2012). PLN is a pentameric protein that, when phosphorylated, alleviates ATP2A2 inhibition and may stimulate SR calcium uptake in cardiomyocytes (Kaliman et al. 2005). Phosphorylation of PLN is mediated by myotonin-protein kinase (DMPK), a SR-bound homodimeric enzyme (Bush et al. 2000, Zhang & Epstein 2003).
Literature References
PubMed ID Title Journal Year
12832055 Homodimerization through coiled-coil regions enhances activity of the myotonic dystrophy protein kinase

Epstein, HF, Zhang, R

FEBS Lett. 2003
10913253 Myotonic dystrophy protein kinase domains mediate localization, oligomerization, novel catalytic activity, and autoinhibition

Perryman, MB, Helmke, SM, Birnbaum, RA, Bush, EW

Biochemistry 2000
15598648 Myotonic dystrophy protein kinase phosphorylates phospholamban and regulates calcium uptake in cardiomyocyte sarcoplasmic reticulum

Chien, KR, Lam, JT, Ruiz-Lozano, P, Palacin, M, Reddy, S, Kaliman, P, Zorzano, A, GutiƩrrez, JC, Catalucci, D, Kondo, R

J. Biol. Chem. 2005
22427649 Hydrophobic imbalance in the cytoplasmic domain of phospholamban is a determinant for lethal dilated cardiomyopathy

Young, HS, Trieber, CA, Ceholski, DK

J. Biol. Chem. 2012
Catalyst Activity

protein serine/threonine kinase activity of DMPK dimer [sarcoplasmic reticulum membrane]

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