Glycogenesis

What is the basis of glycogenesis?

Synthesis of glycogen

• Glucose —> glycogen

Where does glycogenesis occur?

Liver and muscle cells

Role of glycogenesis in the muscle?

Excess glucose is stored as glycogen for energy storage

Role of glycogenesis in the liver?

In response to insulin, glucose is removed from the blood

• Because insulin signals high blood glucose levels

What is the enzyme for glycogenesis?

Glycogen synthase

How is glycogenesis activated?

By glucose-6-phosphate as an indicator of excess glycose

How is glycogenesis inhibited?

By high levels of ATP and glucose-6-phosphate because it inhibits glycogen phosphorylase

• Low insulin levels

• High glucagon, epinephrine

Formation of amylose chains

What does the synthesis of new glycogen require?

What occurs to the residues

Function of glycogen synthase

Require: The presence of existing glycogen chains and glucosyl residues from UDP-glucose

Residues: Are transferred to the C-4 terminus of an existing glycogen chain in a a-1,4-glycosidic linkage

Function of glycogen synthase: Rate limiting step in glycogen synthesis

Formation of branch chains and further growth

How does this occur?

Segments of the amylose chain are transferred to a C-6 hydroxyl group of glucosyl residue that is 4 residues away length before a segment is transferred from it