Glucose metabolism

arne1's version from 2015-09-22 14:41


Question Answer
glycogen synthase is activated whendephosphorylated
high insulin levels activateprotein phosphatase 1 (cleaves phsophate from glycogen synthase (dephosphorylating and activating it)
effect of high glucagon, epinephrine concentrationphosphorylated glycogen synthase (inactive) via protein kinase A
Debranching enzyme activity4:4 transferase (from limit dextrin to longer branches) and alpha 1-->6 glucosidase which cuts at branch point.
Glycogen synthase is activated byglucose 6-P (muscle and liver)
Glycogen phosphorylase is inhibited byglucose 6-P and ATP (muscle and liver)
in liver, glycogen phosphorylase is inhibited byGlucose (allosteric inhibition)
in muscle, glycogen phosphorylase is activated byAMP (allosteric activation)


Question Answer
Glycogen synthase is active whendephosphorylated
glycogen phosphorylase is active whenphosphorylated
glycogen phosphorylase kinasephophorylates and activates glycogen phosphorylase
glycogen phsophorylase kinase is itself activated byphsophorylation by protein kinase A of the cAMP-messenger system


Question Answer
glycogen phosphorylase kinase is allosterically activated byCa++ (bind to calmodulin subunit). enzyme is active w/o phosphorylation.
epinephrinecauses protein kinase A to phosphorylate (activate) glycogen phosphorylase kinase --> activates glycogen phosphorylase.
muscle isozyme of glycogen is activated byAMP (no phosphorylation)


Question Answer
Glycogen storage disease (GSD) type 0glycogen synthase deficiency (rare)
Glycogen storage disease (GSD) type 1 (von gierke)glucose 6-phosohatase. Hepatonephromegaly. high glycogen content in liver and kidney with normal structure.
Glycogen storage disease (GSD) type II (pompe)lysosomal alpha-glucosidase. Defective glycogen degradation in lysosomes by acid maltase (alpha 1-4 glucosidase)
Glycogen storage disease (GSD) type III (Cori)Debranching enzyme
Glycogen storage disease (GSD) type IV (anderson)branching enzyme
Glycogen storage disease (GSD) type V (McArdle)Myophosphorylase
Glycogen storage disease (GSD) Type VI (Hers)Hepatophosphorylase
Glycogen storage disease (GSD) Type VII (Tarui)PFK in muscle and in RBC

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