07 Glycogen

• 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