Glucose has to be phosphorylated to activate glycogen synthase, but not to inactivate glycogen phosphorylase in hepatocytes.
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 of 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.
Carabaza
A
A
Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Spain.
Ciudad
C J
CJ
Baqué
S
S
Guinovart
J J
JJ
D000818:Animals; D003847:Deoxyglucose / Q000031:analogs & derivatives / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005947:Glucose / Q000031:analogs & derivatives* / Q000494:pharmacology; D005958:Glucosephosphates / Q000378:metabolism*; D006006:Glycogen Synthase / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D008297:Male; D006005:Phosphorylases / Q000378:metabolism*; D051381:Rats
D005958:Glucosephosphates; C003002:5-thio-D-glucose; C006584:1,5-anhydroglucitol; D003847:Deoxyglucose; D006005:Phosphorylases; D006006:Glycogen Synthase; D005947:Glucose; C037904:6-deoxyglucose