title: Are there errors in glycogen biosynthesis and is laforin a repair enzyme?
abstract: Glycogen, a branched polymer of glucose, is well known as a cellular reserve of metabolic energy and/or biosynthetic precursors. Besides glucose, however, glycogen contains small amounts of covalent phosphate, present as C2 and C3 phosphomonoesters. Current evidence suggests that the phosphate is introduced by the biosynthetic enzyme glycogen synthase as a rare alternative to its normal catalytic addition of glucose units. The phosphate can be removed by the laforin phosphatase, whose mutation causes a fatal myoclonus epilepsy called Lafora disease. The hypothesis is that glycogen phosphorylation can be considered a catalytic error and laforin a repair enzyme.
authors.affiliation: Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indiana, USA. proach@iupui.edu
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Roach
mesh_terms: D000818:Animals; D004734:Energy Metabolism; D006003:Glycogen / Q000096:biosynthesis* / Q000235:genetics; D006006:Glycogen Synthase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D020192:Lafora Disease / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010766:Phosphorylation / Q000235:genetics; D054558:Protein Tyrosine Phosphatases, Non-Receptor / Q000235:genetics / Q000378:metabolism*
chemical_list: D006003:Glycogen; D006006:Glycogen Synthase; D054558:Protein Tyrosine Phosphatases, Non-Receptor; C114990:EPM2A protein, human