Phosphate incorporation during glycogen synthesis and Lafora disease

Vincent S. Tagliabracci, Christian Heiss, Chandra Karthik, Christopher J. Contreras, John Glushka, Mayumi Ishihara, Parastoo Azadi, Thomas D. Hurley, Anna A. Depaoli-Roach, Peter J. Roach

Research output: Contribution to journalArticlepeer-review

85 Scopus citations


Glycogen is a branched polymer of glucose that serves as an energy store. Phosphate, a trace constituent of glycogen, has profound effects on glycogen structure, and phosphate hyperaccumulation is linked to Lafora disease, a fatal progressive myoclonus epilepsy that can be caused by mutations of laforin, a glycogen phosphatase. However, little is known about the metabolism of glycogen phosphate. We demonstrate here that the biosynthetic enzyme glycogen synthase, which normally adds glucose residues to glycogen, is capable of incorporating the β-phosphate of its substrate UDP-glucose at a rate of one phosphate per approximately 10,000 glucoses, in what may be considered a catalytic error. We show that the phosphate in glycogen is present as C2 and C3 phosphomonoesters. Since hyperphosphorylation of glycogen causes Lafora disease, phosphate removal by laforin may thus be considered a repair or damage control mechanism.

Original languageEnglish (US)
Pages (from-to)274-282
Number of pages9
JournalCell Metabolism
Issue number3
StatePublished - Mar 2 2011

ASJC Scopus subject areas

  • Physiology
  • Molecular Biology
  • Cell Biology


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