Flashcards in EXAM3_Glycogen_Metabolism Deck (15)
How much liver glycogen is stored? How long will that battery last?
100grams of glycogen stored in liver
Will last about 30 hours
How much muscle glycogen is stored?
400 grams stored in muscle
Lasts weeks- b/c not used anywhere except the muscle
High IG ratio has what effect on glycogen in the liver?
GLUT2 uptake from portal circulation
Glucokinase (High KmVmax) Traps glucose inside liver
-liver stores 100g glycogen
High IG ratio has what effect on glycogen in muscle and adipose?
GLUT4 uptake from systemic circulation
Hexokinase traps glucose in peripheral tissue cells
Muscle glycogenesis up to 400g stored
What are the three regulatory enzymes of Glycogenesis?
Which one is rate limiting enzyme ?
1. UDP-glucose pyrophosphorylase,
2. Glycogen synthase**, (Rate limiting)
3. Branching enzyme
What core protein and amino acid required for glycogenesis?
Glycogenin & Tyrosine
Glycogenolysis 3 enzymes?
What is rate limiting?
1. Glycogen phosphorylase* (rate limiting)
2. Debranching Enzyme
What should you think when you see Glycogen phosphorylase?
-alpha 1,4 cleavage (glycosidic bond)
-VitB6 is coenzyme (Pyridoxal phosphate)
-Glucose 1-P is product
-4 glucosyl units
-removes outer 3 glucosyl residues
What enzyme converts G1P to G6P?
G6Pase (liver and renal cortex)
-free glucose released (maintains blood glucose fasting)
What is the significance of exercising muscle glycogenolysis?
G6P enters glycolysis directly (skipping ATP fee)
-also primes TCA
Muscle glycogenolysis is crucial for TCA cycle priming. How?
G6P converted to Pyruvate which is converted to OAA (in the TCA)
During intense exercise where does muscle get its energy from?
Beta Oxidation- not from complete oxidation of glucose
Muscle glycogenolysis required to prime TCA for beta oxidation to work?
Glycogen synthase Activation/Inhibition in the Muscle
Activated by insulin (dephosphorylated form is active)
Inhibited by Epinephrine