Glycogen Flashcards
when does glycogen kick in?
4 hours
when is gluconeogenesis the primary source of energy?
around 24 hours
UDP glucose can be used for
incorporation into proteoglycans or conjugation to steroid hormones
what is necessary for UDP glucose to form glycogen?
glycogenin
what does glycogen synthase do?
it adds UDP glucose in growing alpha 1-4 glycosidic bonds
What does branching enzyme/ amylo 4-6 glycosyl transferase do?
It transfers 5-8 resudies to the glycogenin molc. to make a new branch
glycogen synthase is active when
it is not phosphorylated, in the fed state
Mcardles disease
defect in glycogen phosphorylase, glycogen builds up
what activtes glycogen synthase
insulin and G6P
what does debrancher enzyme do?
It transfers 3 glcosyl residues and adds them at the end of the longer chain
What are the two activities of the debrnahcer enzyme?
1) transfer of 3 glocosyl residues to the end of the longer chain and
2) amyo1-6 glucosidase, which cleaves the one remainig apha 1-6 branch ā> net glucose
IMPORTANT: For every branch of glycogen you get
1 glucose and 7-9 glucose 1-Pās
Pompe disease
problem w lysosomal alpha 1-4 glucosidase leading to accumulation of glycogen in vaculous
Why does glucose inhibit glycogen phosphorylase in the liver but not in the msucle?
there is no glucose 6 phosphatase in the muscle
Glucagon does what to glycogen phosphorylase and ksynthetase
glucagon activtes PKA which directly phosphorylaes glycogen synthase making it inactive. It also phosphorylates Glycogen phosphorylase kinase
