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AMP-activated protein kinase phosphorylates and inactivates liver glycogen synthase

AMP-activated protein kinase phosphorylates and inactivates liver glycogen synthase

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Authors

  • Laurent Bultot
  • Bruno Guigas
  • Alexander Von Wilamowitz-Moellendorff
  • Liliane Maisin
  • Didier Vertommen
  • Nusrat Hussain
  • Monique Beullens
  • Joan J. Guinovart
  • Marc Foretz
  • Benoit Viollet
  • Kei Sakamoto
  • Louis Hue
  • Mark H. Rider

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Info

Original languageEnglish
Pages193-203
Number of pages11
JournalBiochemical Journal
Journal publication date1 Apr 2012
Volume443
DOIs
StatePublished

Abstract

Recombinant muscle GYS1 (glycogen synthase 1) and recombinant liver GYS2 were phosphorylated by recombinant AMPK (AMP-activated protein kinase) in a time-dependent manner and to a similar stoichiometry. The phosphorylation site in GYS2 was identified as Ser(7), which lies in a favourable consensus for phosphorylation by AMPK. Phosphorylation of GYS1 or GYS2 by AMPK led to enzyme inactivation by decreasing the affinity for both UDP-Glc (UDP-glucose) [assayed in the absence of Glc-6-P (glucose-6-phosphate)] and Glc-6-P (assayed at low UDP-Glc concentrations). Incubation of freshly isolated rat hepatocytes with the pharmacological AMPK activators AICA riboside (5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside) or A769662 led to persistent GYS inactivation and Ser(7) phosphorylation, whereas inactivation by glucagon treatment was transient. In hepatocytes from mice harbouring a liver-specific deletion of the AMPK catalytic alpha 1/alpha 2 subunits, GYS2 inactivation by AICA riboside and A769662 was blunted, whereas inactivation by glucagon was unaffected. The results suggest that GYS inactivation by AMPK activators in hepatocytes is due to GYS2 Ser(7) phosphorylation.

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