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Glucose has to be phosphorylated to activate glycogen synthase, but not to inactivate glycogen phosphorylase in hepatocytes
Author(s) -
Carabaza Assumpta,
Ciudad Carlos J.,
Baqué Susanna,
Guinovart Joan J.
Publication year - 1992
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(92)80381-p
Subject(s) - glycogen phosphorylase , glycogen synthase , glycogen branching enzyme , phosphorylase kinase , glycogen debranching enzyme , glycogenesis , glycogen , biochemistry , chemistry , atp synthase , glucose 6 phosphate , enzyme , phosphorylation , hepatocyte , biology , medicine , in vitro
2‐Deoxyglucose and 5‐thioglucose, in the same fashion as glucose, cause the inactivation of the rat hepatocyte glycogen phosphorylase and the activation of glycogen synthase. However, 6‐deoxyglucose and 1,5‐anhydroglucitol inactivate phosphorylase without increasing the activation state of glycogen synthase. With 3‐ O ‐methylglucose no changes in the activity or these enzymes occurred. These results prove that while glucose is the molecule that triggers the inactivation of phosphorylase, glucose 6‐phosphate is the signal for glucose synthase activation and that a metabolite control of the activation state of glycogen synthase is operative in hepatocytes.