07 Glycogen

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• muscles cannot release glucose from glycogen

• 1-4 linear linkage
• 1-6 branching
• branching makes it more soluble and better storage

• UDP: uridine

• lysosomes can collect glycogen and break it down to glucose

• glycogen phosphorylase shrink purple link down to 3 or so
• debranching enzyme moves purple to red, releasing one molecule of glucose (green)

• glucagon/E phosphorylates both enzymes both have opposite effects
• glycogen phosphorylase activity increases
• glycogen synthase activity decreases

• insulin results in dephosphorylation of both and opposite effects

• activate glycogen phosphorylase in absence of hormones
• immediate activation instead of hormonal

Glycogen Storage Diseases

• liver defective enzyme: hypoglycemia
• enzyme defective in muscle: weakness

Von Gierke

• can't release glucose between meals
• can't get glucose out of liver = hepatomegaly

• muscles will be ok
• no symptoms of muscle weakness

• consume corn starch between meals

Pompe

• liver is ok, continue make glucose
• no hypoglycemia symptoms

• entrapment of glycogen inside muscle cells
• enlarged tongue classic finding

Cori

• gluconeogenesis intact from other sources: hypoglycemia not as severe
• no glucose in muscles either: weakness

• usually no seizures
• muscle symptoms distinguish from Von Gierke

McArdle

• no liver problems, no hypoglycemis
• muscle difficulties
• can get muscle damage with exercise