Glycogen Metabolism & Glycogen Storage Diseases Flashcards
rate limiting enzyme for glycogen synthesis
glycogen synthase
rate limiting enzyme for glycogenolysis
glycogen phosphorylase
what promotes breakdown of glycogen in liver? in muscle?
liver–> glucagon and epinephrine
muscle–> epinephrine
how does glucagon or epi signal for glycogen to be broken down
increases cAMP—> protein kinase A–> phosphorylates glycogen phosphorylase, rendering it active–> glycogenolysis
what signals glycogen phosphorylase to turn off
insulin –> activates receptor tyrosine kinase–> activates protein phosphatase–> dephospharylate glycogen synthase, rendering it inactive
what activates glycogen phosphorylase in muscle tissue to coordinate glycogenolysis with muscle activity
Ca2+/ calmodulin–> also phosphorylates glycogen phosphorylase
glycogen phosphorylase deficiency
McArdles disease (type V)
glucose-6-phosphatase deficiency
Von gierke’s disease (type 1)
lactic acidosis, hyperlipidemia, hyperuricemia (gout)
Von Gierke’s disease (type 1)
alpha- 1,6 glucosidase deficiency (branching enzyme)
Cori’s disease (type III)
alpha 1,4 glucosidase deficiency
Pompe’s disease (type II)
*is a lysosomal enzyme!!
Cardiomegaly
Pompe’s disease, infantile type
Diaphragm disease leading to respiratory failure, gradal muscle weakess
Pompe’s disease, adult type
Increased glycogen in liver (hepatomegaly), severe fasting hypoglycemia, increases lactic acid levels
Von Gierke’s disease
hepatomegaly, hypoglycemia, hyperlipidemia, normal lactic acid levels. enzyme?
Cori’s disease (type III)
- alpha 1, 6 glucosidase (debranching enzyme)
