Biochemistry Ch. 25-Glycogen Synthesis

UDP-glucose pyrophosphorylase

adds UTP to glucose 1-phosphate to make UDP-glucose

Glycogen synthase 

takes a glucose molecule from UDP-glucose and adds it to the C4 terminal residue of a glycogen chain via a-1,4-glycosidic bond (requires a primer)

Glycogenin

makes the primer for glycogen synthase, an oligosaccharide residue 10-20 units long (autoglycosylation)

1,4-a-glucan-branching enzyme

breaks an a-1,4 linkage and takes about 7 glucoses and reattaches them via a-1,6 linkage

Protein Kinase A role in glycogen synthesis 

inactivates glycogen synthase by converting it into the inactive phosphorylated form

Glycogen synthase kinase

inactivates glycogen synthase

Protein Phosphatase I

activates glycogen synthase by turning it to the active form, and also inhibits phosphorylase kinase and phosphorylase a

Phosphoglucomutase

converts glucose 1-phosphate to glucose 6-phosphate

How much ATP does glycogen make?

31 molecules (only requires 2 ATP)

Insulin

stimulates glycogen synthesis by activating protein kinases that inactivate glycogen synthase kinase, PPI then makes the active form of synthase

Phosphorylase a

the glycose sensor in liver cells