Glycogen Degradation

Study the term answer with definition.

What is the committed step for Glycogen Degradation?

Glycogen Phosphorylase

What is Activity One for Glycogen Degradation? What does it do?

Glycogen Phosphorylase. It cleaves and adds phosphate to glycogen to form glycose-1-phosphate.

What is activity two for glycogen degradation? What does it do?

Transferase. moves 3 residues from branch points.

What is activity three for glycogen degradation? what does it do?

alpha-1,6, glucosidase. debranches and hydrolyzes 1,6 linkages.

what is activity four for glycogen degradation? what does it do?

hexokinase. glucose is released phosphorylated

what is activity five for glycogen degradation? what does it do?

phosphoglucomutase. glucose-1-phsophate→glucose-6-phosphate

What is activity six for glycogen degradation? what does it do? What’s so special about this activity?

Glucose-6-phsophatase. Dephosphorylates glucose for transport out of the cell. IT IS ONLY IN THE LIVER.

What is phosphorylase a?

R-state. active. phosphorylated.

What is phosphorylase b?

T-state. Less active. Dephosphorylated.

How is phosphorylase regulated in muscle tissue?

T-state, phosphorylase b

How is phosphorylase regulated in the liver?

R-state, phosphorylase a

How does insulin regulate phosphorylase in the liver?

it dephosphorylates so less active. Less glycogen breakdown

How does glycogen regulate phosphorylase in the liver?

phosphorylation so more active and more glycogen breakdown.

How does high ATP and glucose regulated phophorylase in the muscle?

low phosphorylase activity

how does high AMP regulate phosporylase in the muscle?

high phosphorylase activity

how does epinephrine regulate phosphorylase in the muscle?

conversion to the a form

How is phosphorylase regulated by phosphorylation?

alpha and beta phosphorylation by protein kinase A = increased activity

How is phosphorylase regulated by calcium binding?

Calmodulin binding = activation