Glycogenesis

Step 1

Glucose is brought into liver by a transporter called GLUT-2

Step 2

Glucose is phosphorylated to glucose-6-phosphate by the enzyme glucokinase in the liver. This uses ATP

hexokinase in muscle cells

Step 3

Glucose-6-phosphate is converted to glucose-1-phosphate by the enzyme phosphoglucomutase.

Step 4

By using UTP, glucose-1-phosphate is converted to UDP-glucose, which is the activated form of glucose.

The enzyme used for this is UDP-glucose pyrophosphorylase.

Step 5

the bond between UDP and the carbon 1 of glucose molecule breaks and the glucose links its carbon 1 to glycogenin

more glucose detach from UDP and makes alpha-1,4 glycosidic bonds with the existing glucose attached to the glycogenin for the purpose of priming

step 6

glycogen synthase comes in and adds more glucose to the glucose-glycogenin chain, creating more alpha- 1,4 glycosidic linkages between the glucose molecules

step 7

Branching enzyme breaks the alpha-1,4 glycosidic linkages in the glucose-glycogen chain and links the chunk of glucose molecules that were cut from the chain to the 6 carbon position of a glucose that is still on the glucose-glycogenin chain

this causes alpha-1,6 glycosidic linkages to form and introduce branches into the glucose-glycogenin chain

step 8

glycogen synthase continues to add glucose to the glucose-glycogenin chain and branching enyzme continues to cut and create branches

the glucose-glycogenin chain with its branches is called glycogen

Role of insulin

Insulin promotes glycogen synthase to create glycogen from glucose

Role of epinephrine and glucagon

Epinephrine inhibits glycogen synthase leading to increased glucose availability for energy during stress responses.

Rate limiting step

Conversion of UDP glucose to glycogen by glycogen synthase