Glycogenesis Flashcards
Common enzyme: glycogenesis and gluconeogenesis
glucose-6-phosphatase
muscle cells lack this enzyme therefore:
1) cannot perform gluconeogenesis
2) cannot convert G6P to glucose –> trapped in muscle cell
Second function of debranching enzyme
Debranching enzyme works on alpha-1,6 glycosidic linkages.
4 glucose molecules away from branch point –> glycogen phosphorylase stops working
alpha-1,6-glucosidase acts as transferase.
3 glucose molecules transfered.
last glucose cleaves alpha-1,6 glycosidic linkage
How does epinephrine activate glycogenolysis?
Beta-adrenergic receptor stimulated
Adenylyl cyclase activated
Glycogen phosphorylase activated –> glycogenolysis
Deficiency in glycogen phosphyorylase
McArdle disease (GSD type V)
Deficiency in glucose-6-phosphatase
von Gierke (GSD type I)
- common enzyme in gluconeogenesis, glycogenolysis (G6P to glucose)
- not found in muscle
Deficiency in alpha-1,6-glucosidase
Cori disease (GSD type III)
Glycogen is incompletely broken down (just 1 ,6 linkages remain)
Deficiency of alpha-1,4-glucosidase in lysosomes
Pompe disease (II)
alpha-1,4-glucosidase found in lysosomes.
Rhabdomyolysis
Muscle cramping
Normal muscle cells
McArdles (V)
Severe fasting hypoglycemia Hepatomegaly Enlarged kidneys Elev. serum lactate Elev. uric acid Hypertriglyceridemia
von Gierke (I) Deficiency in glucose-6-phosphatase
*remember: glucose-6-phosphatase is found in LIVER, KIDNEY, ENTEROCYTES (energy sharing cells)
Mild fasting hypoglycemia
No elevation in lactate
No elevation in uric acid
Cori disase (III)
Cardiomegaly + glycogen storage disease
Infantile Pompe disease
Respiratory failure + glycogen storage disease
Late-onset Pompe
Enzyme that converts glucose-6-phosphate to glucose?
Deficiency results in what disease?
glucose-6-phosphatase
von Gierke disease
