Glycogen Synthesis and Degradation

Question 1

Gluconeogenesis: substrates, glucose, diseases

Answer 1

substrates: glycerol (TAG in adipose), lactate (muscle), amino acids (alpha keto acids from protein) = UDP-glucose
location: liver and skeletal muscle

Von Gierke, Pompe, Cori, McAdrle, Hers

Question 2

Glycogenesis: enzyme, regulators

Answer 2

Glycogen synthase (UDP glucose)

(+) g6p, insulin, cortisol
(-) epi, glucagon, cAMP

Question 3

Glycogenolysis: enzyme, regulators

Answer 3

glycogen phosphorylase (B6)

(+) epi, glucagon, AMP
(-) g6p, insulin, ATP

Question 4

Glycogen synthase deficiency

Answer 4

decrease liver glycogen content, fasting hypoglycemia

Question 5

McArdle syndrome

Answer 5

Skeletal muscle: glycogen phosphorylase deficiency

liver enzymes normal, no rise in blood lactate, high level of glycogen in muscle
benign

cramping weakness in muscle after exercise

Question 6

Hers disease

Answer 6

deficiency of liver glycogen phosphorylase

mild fasting hypoglycemia

Question 7

Pompe disease

Answer 7

lysosomal alpha 1,4 glucosidase deficiency

heart liver muscle

too much glycogen in lysosomes, normal blood sugar

cardiomegaly

Question 8

Cori disease

Answer 8

1,4 or 1,6 transferase deficiency

fasting hypoglycemia, abnormal glycogen structure

Question 9

Von Gierke disease

Answer 9

G6phosphatase deficiency

liver and kidney (muscle doesn’t have this enzyme)

fatty liver, hepato and renomegaly

low blood glucose, high pyruvate, high lactate, high uric acid